Longer-Wavelength-Absorbing, Extended Chalcogenorhodamine Dyes

Article abstract of DOI:10.1021/acs.organomet.6b00255

Extended rhodamines were prepared by inserting an additional fused benzene ring into the rhodamine xanthylium core. The synthesis of "bent" dyes 4-E (E = S, Se, Te) began with regioselective lithiation of the 1-position of N,N-diisopropyl 6-dimethylamino-2-naphthamide (11b) with n-BuLi/TMEDA (≥25:1 1- vs 3-lithiation) followed by addition of a dichalcogenide electrophile. The synthesis of "linear" dyes 5-E (E = S, Se, Te) began with regioselective lithiation of the 3-position of N,N-diethyl 6-dimethylamino-2-naphthamide (11a) with lithium tetramethylpiperidide (≥50:1 3- vs 1-lithiation) followed by addition of a dichalcogenide electrophile. Dyes 4-E and 5-E have absorption maxima in the 633-700 nm range. Dyes 4-E generate singlet oxygen upon irradiation while dyes 4-S and 5-S are highly fluorescent, with quantum yields for fluorescence of 0.47 and 0.18, respectively. DFT calculations were performed on the 4-E and 5-E chromophores. For the dyes 4-E, the lowest energy excitation is due solely to the HOMO-LUMO transition. For dyes 5-E, the lowest energy excitation is a combination of two excitations, both having contributions from the HOMO to LUMO and HOMO-1 to LUMO.

Full text of DOI:10.1021/acs.organomet.6b00255

Article
pubs.acs.org/Organometallics
Longer-Wavelength-Absorbing, Extended Chalcogenorhodamine
Dyes
†
,‡
,†
Mark W. Kryman, Theresa M. McCormick,* and Michael R. Detty*
†Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260-3000, United States
‡Department of Chemistry, Portland State University, Portland, Oregon 97207, United States
*
S Supporting Information
ABSTRACT: Extended rhodamines were prepared by insert-
ing an additional fused benzene ring into the rhodamine
xanthylium core. The synthesis of “bent” dyes 4-E (E = S, Se,
Te) began with regioselective lithiation of the 1-position of
N,N-diisopropyl 6-dimethylamino-2-naphthamide (11b) with
n-BuLi/TMEDA (≥25:1 1- vs 3-lithiation) followed by
addition of a dichalcogenide electrophile. The synthesis of
“
linear” dyes 5-E (E = S, Se, Te) began with regioselective
lithiation of the 3-position of N,N-diethyl 6-dimethylamino-2-
naphthamide (11a) with lithium tetramethylpiperidide (≥50:1
3
- vs 1-lithiation) followed by addition of a dichalcogenide electrophile. Dyes 4-E and 5-E have absorption maxima in the 633−
700 nm range. Dyes 4-E generate singlet oxygen upon irradiation while dyes 4-S and 5-S are highly fluorescent, with quantum
yields for fluorescence of 0.47 and 0.18, respectively. DFT calculations were performed on the 4-E and 5-E chromophores. For
the dyes 4-E, the lowest energy excitation is due solely to the HOMO−LUMO transition. For dyes 5-E, the lowest energy
excitation is a combination of two excitations, both having contributions from the HOMO to LUMO and HOMO-1 to LUMO.
INTRODUCTION
500−550 nm window for absorption maxima in the rhodamines
is one of their limitations since it is outside the 600−900 nm
window of maximum transparency in biological tissue. Heavy
chalcogen analogues of the rhodamines (1-S, 1-Se, and 1-Te,
Chart 1) absorb in the 570−600 nm window with the
tellurorhodamines having the longest wavelength absorption
■
The cationic rhodamine dyes such as tetramethylrosamine (1-
O, Chart 1) are based on the xanthylium nucleus. The
rhodamines are important chromophores in chemistry and
biology and are used as laser dyes, fluorescent labels, and
fluorescence emission standards where their high fluorescence
11,12
maxima.
More recently, chalcogenorhodamines with addi-
1
−10
quantum yields and photostabilities are exploited.
The
tional fused rings to restrict rotation of the 3- and 6-amino
substituents in the xanthylium core extend absorption maxima
13−15
Chart 1. Structures of the Chalcogenorosamines 1-E,
Extended Fluoresceins 2 and 3, and Extended
Chalcogenorhodamines 4-E and 5-E
to 630 nm.
The longer wavelength-absorbing seleno- and
tellurorhodamines are also effective photosensitizers for the
1
1,14,15
generation of singlet oxygen,
the generation of photo-
16−18
currents,
9and for the photochemical reduction of protons
1
to hydrogen.
Another approach to longer-wavelength-absorbing xanthene
dyes focused on the extension of the chromophore through
7a,20,21
additional fused benzene rings.
Compounds 2 and 3
(
Chart 1) are representative examples of extended fluorescein-
related molecules with longer wavelengths of absorption and
emission. Chalcogenorhodamine-related structures with similar
additional fused rings should absorb and emit at longer
wavelengths than their xanthylium-based analogues.
Herein, the syntheses of extended chalcogenorhodamine
chromophores are described utilizing the regioselective metal-
ation of 6-dimethylamino-2-naphthamides at the 1-position for
the preparation of dyes 4-E (Chart 1) and the 3-position for the
Received: March 30, 2016
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.6b00255
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Scheme 1. Retrosynthetic Analysis of Extended Rhodamines 4-E and 5-E from 6-Dimethylamino-2 Naphthamide Derivatives 11
Scheme 2. Synthesis of 6-Dimethylamino-2-naphthamide Derivatives 11
preparation of dyes 5-E. The photophysical properties of 4-E
and 5-E are compared to those of the parent rhodamine 1-O
and the heavier chalcogen analogues 1-S, 1-Se, and 1-Te (Chart
addition of 1,4-diazabicyclo[2.2.2]octane (DABCO). Overall,
naphthoate 12 was isolated in 99% yield. Ester 12 was
converted to amides 11 via the addition of lithium diethylamide
to give 11a in 97% yield or lithium diisopropylamide to give
11b in 85% yield as shown in Scheme 2.
1). The extended conjugation in 4-E and 5-E increases the
absorption maxima (λmax) to wavelengths >640 nm. The
extended chalcogenorhodamine chromophores were also
examined computationally using density functional theory
In our synthetic approach to the 1-E derivatives and to other
chalcogenorhodamines, directed metalations of 4-dimethylami-
no-substituted benzamide derivatives with s-BuLi/TMEDA or
t-BuLi/TMEDA gave 2-lithio-4-dimethylaminobenzamides in
excellent yield, which then reacted with dichalcogenides 8-E to
(
DFT).
RESULTS AND DISCUSSION
■
22
give the xanthone precursors. A similar approach with
naphthamides 11 should lead to precursors to xanthones 6-E
from 1-lithio-2-naphthamides 9 and to 7-E from 3-lithio-2-
naphthamides 10. However, the regiochemical preference for
metalation with t-BuLi or s-BuLi/TMEDA to give 9 and/or 10
is not clear.
Synthesis of Extended Rhodamine Dyes 4-E and 5-E.
The approach to extended rhodamine dyes 4-E and 5-E is
shown in the retrosynthetic analysis of Scheme 1. Addition of
an aryl Grignard reagent to the appropriate extended xanthone
6
-E or 7-E followed by an acidic workup would give the
cationic extended rhodamine. The extended xanthones 6-E and
-E can be prepared via addition of dichalcogenides 8-E to 1-
The regioselectivity of directed metalation of 2-substituted
7
lithio-6-dimethylamino-2-naphthamide 9 or 3-lithio-6-dimethy-
lamino-2-naphthamide 10, respectively, followed by cyclization
of the resulting amide derivatives. The selective lithiation of a 6-
dimethylamino-2-naphthamide 11 to deliver 9 or 10 is key to
the synthetic plan.
Synthesis of 6-dimethylamino-2-naphthamide derivatives 11
began with methylation of 6-amino-2-naphthoic acid with
iodomethane and sodium carbonate in DMF at 110 °C
naphthalenes varies with the specific substrate, directing group,
23−27
base, and solvent conditions.
The regioselective synthesis
of 2,3-di- and 1,2,3-trisubstituted naphthalenes via a directed
metalation strategy with N,N-diethyl-O-naphthyl-2-carbamates
2
8
has been recently reported. However, studies of the
regioselectivity of directed ortho-metalation of naphthyl-2-
amides has been limited and has given poor selectivity as shown
2
3
in Scheme 3. The directed ortho-metalation of N,N-
diisopropyl 2-naphthamide with s-BuLi/TMEDA at −78 °C
in THF followed by reaction with DMF gave 1,2- and 2,3-
disubstituted naphthalenes 13 and 14 in 22% and 10% isolated
(
Scheme 2). Formation of methyl 6-dimethylamino-2-naph-
thoate 12 was accompanied by formation of some of the 6-
trimethylammonium derivative from over alkylation. The
quaternary trimethylammonium salt was demethylated via the
23
yields, respectively. Bulky bases or bulky amide groups have
B
DOI: 10.1021/acs.organomet.6b00255
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Scheme 3. Directed Metalations of 2-Naphthamide
Derivatives from Reference 23
6). Directed metalation of 11b with n-BuLi/TMEDA followed
by the addition of the dichalcogenides 8-E (Scheme 5) gave the
1
,2-disubstituted products 19-E as the major products in these
reactions with the 2,3-disubstituted regioisomers 20-E present
1
at ≤4% by H NMR spectroscopy (Table 1, entries 7−9).
Steric interactions between the isopropyl protons on the
amides with the peri 8-hydrogen on the naphthamide ring
(
inset of Scheme 5) would serve to shield the 3-proton from
deprotonation while allowing approach of the base to the 1-
proton. The dichalcogenide electrophile 8-E had minimal
impact on the reaction as shown in the specific products of
Scheme 5: sulfide 19-S was isolated in 80% yield, selenide 19-
Se was isolated in 82% yield, and telluride 19-Te was isolated in
94% yield.
allowed selective metalation at the 1-position but not the 3-
position. Directed metalation of N,N-diethyl 6-methoxy-2-
naphthamide with t-BuLi at −78 °C in THF and quenching
with iodoethane gave N,N-diethyl 6-methoxy-1-ethyl-2-naph-
thamide, the product of metalation at the 1-position, in 68%
2
8
yield. Similarly, directed metalation of N,N-diisopropyl 6-
methoxy-2-naphthamide with n-BuLi at −78 °C in THF
followed by reaction quenching with iodoethane gave N,N-
diisopropyl 6-methoxy-1-ethyl-2-naphthamide in 95% isolated
The preferential lithiation of the 3-position of naphthamide
11a was approached using bulky lithium amide bases. Our
reasoning was that bulky dialkylamide bases would have
unfavorable steric interactions with the peri-hydrogen at the
28
yield, again, from metalation at the 1-position. With the
diisopropylamide, nucleophilic addition of n-BuLi was not
observed.
8
-position as they approached the proton on the 1-position
inset of Scheme 6). Approach to the proton on the 3-position
would lack this interaction and preferential deprotonation at
(
Amide 11a was subjected to directed metalation with s-BuLi
and TMEDA at −78 °C, and the resulting mixture of anions
was quenched with dichalcogenides 8-E (Scheme 4).
Inseparable mixtures of 15-E/16-E were isolated. Lithiation at
the 1-position was favored by a ratio of 2.5:1 to 3.3:1 as
28
the 3-position would be observed. Initial attempts to lithiate
1a with LDA (1.0−3.0 equiv) in THF at −78 °C were
1
unsuccessful over a range of lithiation times (1 min−1.5 h),
with quantitative recovery of amide 11a. The use of lithium
tetramethylpiperidide (LiTMP) was more successful (Table 1,
entries 10−12). The addition of 3.0 equiv of LiTMP to a stirred
solution of 11a in THF at −78 °C with a 1.5 h lithiation time
before addition of 3.0 equiv of the dichalcogenide electrophile
1
determined by H NMR spectroscopy (Supporting Informa-
tion) as shown in Table 1, entries 1−3. The structures of 15-E
and 16-E were assigned unambiguously by cyclization of the
29
mixtures with POCl /Et N to give extended chalcogenox-
3
3
8
-E gave the 2,3-disubstituted regioisomers 16-E in ≥50:1
regioselectivity. The 1,2-regioisomers 15-E were present as
2% of the crude product mixture if present at all (Supporting
anthones 6-E and 7-E in a ratio of 2.5:1 to 3.3:1 (Scheme 4).
The chalcogenoxanthones 6-E and 7-E were separable by
chromatography on SiO2.
The reaction of t-BuLi with 11a at −78 °C followed by
addition of diselenide 8-Se gave a 3:1 mixture of 1-substituted
≤
1
Information for H NMR spectra). As shown in Scheme 6, the
dichalcogenide electrophile 8-E had minimal impact on the
reaction: sulfide 16-S was isolated in 55% yield (91% based on
recovered amide 11a), 80% yield, selenide 16-Se was isolated in
50% yield (94% based on recovered amide 11a), and telluride
16-Te was isolated in 53% yield (92% based on recovered
amide 11a). The regioselectivity of lithiation of 11a with
LiTMP was little affected by either shorter reaction times of
11a with LiTMP (5 min to 1.5 h) or by the use of up to 6 equiv
of LiTMP. Shorter reaction times or additional base gave
reduced yields of 20-E.
15-Se and 3-substituted 16-Se, respectively (Table 1, entry 4).
Although the lithiation of the 1-position was favored, the
bulkier t-BuLi did not give improved regioselectivity. We also
examined the directed metalation of 11a with n-BuLi/TMEDA
followed by the addition of 8-Se. Ketones 17 and 18 were
isolated from the product mixture in 40% and 30% yields,
respectively (Table 1, entry 5). Ketone 17 formed as a result of
nucleophilic addition of n-BuLi to the diethylamide moiety,
while the ketone 18 resulted from enolate formation from
ketone 17 and subsequent attack by the electrophile 8-Se.
The impact of increasing the steric bulk of the amide alkyl
groups in N,N-diisopropyl naphthamide 11b on regioselectivity
was next examined. Directed metalation of 11b with s-BuLi and
TMEDA at −78 °C followed by quenching with disulfide 8-S
gave an inseparable 2.5:1 mixture of 19-S/20-S (Table 1, entry
In solution, LiTMP is known to exist as cyclic oligomers and
mixed aggregates as well as bis-solvated dimers, possibly
decreasing its effectiveness in the directed ortho-lithiation of
30−32
amide 11a.
Additives such as TMEDA and LiBr are used
to break up these aggregates, resulting in the formation of an
“open-faced dimer” and monomer type species, respec-
Scheme 4. Metalation of Naphthamide 11a with s-BuLi/TMEDA Followed by Addition of Dichalcogenides 8-E and Cyclization
with POCl /Et N
3
3
C
DOI: 10.1021/acs.organomet.6b00255
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Table 1. Directed Metalations in 6-Dimethylamino-2-naphthamides 11 Followed by Quenching with Dichalcogenides 8-E to
Give 1,2- and 2,3-Substituted Products
entry
amide
metalation conditions
electrophile
ratio 1,2 to 2,3-substitution
1
2
3
4
5
6
7
8
9
11a
11a
11a
11a
11a
11b
11b
11b
11b
11a
11a
11a
s-BuLi/TMEDA, THF, −78 °C
s-BuLi/TMEDA, THF, −78 °C
s-BuLi/TMEDA, THF, −78 °C
t-BuLi, THF, −78 °C
n-BuLi/TMEDA, THF, −78 °C
s-BuLi/TMEDA, THF, −78 °C
n-BuLi/TMEDA, THF, −78 °C
n-BuLi/TMEDA, THF, −78 °C
n-BuLi/TMEDA, THF, −78 °C
LiTMP, THF, −78 °C
8-S
2.5 (15-S):1 (16-S)
2.5 (15-Se):1 (16-Se)
3.3 (15-Te):1 (16-Te)
3 (15-Se):1 (16-Se)
8-Se
8-Te
8-Se
8-Se
8-S
a
−
2.5 (19-S):1 (20-S)
8-S
50 (19-S):1 (20-S)
8-Se
8-Te
8-S
50 (19-Se):1 (20-Se)
25 (19-Te):1 (20-Te)
≤ 1 (15-S):50 (16-S)
1 (15-Se):50 (16-Se)
≤ 1 (15-Te):50 (16-Te)
1
1
1
0
1
2
LiTMP, THF, −78 °C
LiTMP, THF, −78 °C
8-Se
8-Te
a
Only products 17 and 18 were observed and were isolated in 40% and 30% yields, respectively.
3
0,33,34
Scheme 5. Regioselective Metalation of the 1-Position of
N,N-Diisopropyl 2-naphthamide 11b
tively.
Neither LiTMP/TMEDA nor LiTMP-LiBr (3.0
a
equiv for each, 1.5 h lithiation time) had any effect on the
overall yield of 16-E relative to 3.0 equiv of LiTMP alone and a
1
.5 h lithiation time.
While cyclization of the 1,2-disustituted diethylamides 15-E
in the 15-E/16-E mixtures gave the corresponding extended
xanthones 6-E, attempts to cyclize the 1,2-disubstituted
29
diisopropyl naphthamides 19-E with POCl and Et N only
3
3
returned unreacted 19-E. The use of extended reaction times or
the use of larger excesses of reagents did not give any of the
desired extended xanthones 6-E. In contrast, the cyclization of
1
6-E with POCl and Et N gave the extended xanthones 7-E in
3 3
7
2% to 83% isolated yield as shown in Scheme 7. No other
a
Yields in parentheses based on recovered starting material.
products were detected in the reaction mixtures.
Scheme 6. Regioselective Metalation of the 3-Position of
N,N-Diethyl 2-Naphthamide 11a
Scheme 7. Cyclization of Chalcogenides 16-E to Xanthones
a
7-E
Strongly acidic conditions were used to cyclize 1,2-
disubstituted naphthamides 19-E successfully. While concen-
trated H SO or Eaton’s reagent (P O /methanesulfonic
2
4
2
5
35
acid) at 100 °C gave no product formation with recovery
of unreacted 19-E, treating naphthamides 19-E with CF SO H
3
3
at 140 °C for 72 h gave extended xanthones 6-E in 51−62%
isolated yield (Scheme 8). Dealkylated N-isopropyl naphtha-
mides were also isolated from these reactions in <10% yield.
The dealkylated N-isopropyl naphthamides were examined as
the potential precursors to 6-E. When heated with CF SO H at
3
3
a
Yields in parentheses are based on recovered starting material.
1
35 °C, 19-Se gave N-isopropyl naphthamide 21-Se as the
D
DOI: 10.1021/acs.organomet.6b00255
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Scheme 8. Cyclization of 19-E with Trifluoromethanesulfonic Acid
predominant product in 61% yield (<10% 6-Se). When
isolated, 21-Se was resubjected to the cyclization conditions
(
CF SO H, 140 °C) for 20 h, extended xanthone 6-Se was
3 3
isolated as the only product in 39% yield along with recovered
21-Se (Scheme 8).
The addition of Grignard reagents to extended xanthones 6-
E and 7-E leads directly to the extended rhodamine dyes. The
addition of phenylmagnesium bromide to a stirred suspension
of 6-E or 7-E in THF (16 h at reflux) followed by work up with
1
0% aqueous HPF gave dyes 4-E in 90% to 95% isolated yield
6
or dyes 5-E in 84% to 91% isolated yield (Scheme 9).
Scheme 9. Synthesis of Extended Rhodamine Dyes 4-E and
5
-Se
Figure 1. Absorption spectra in dichloromethane for (a) “bent”
extended rhodamines 4-E and (b) “linear” extended rhodamines 5-E.
Spectra are normalized to a common absorbance at λmax
.
Table 2. Values of Absorption Maxima (λmax), Molar
Extinction Coefficients (ε), and Fluorescence Emission
Maxima (λ ) in CH Cl and Quantum Yields for
FL
2
2
Fluorescence (Φ ) and for the Generation of Singlet
FL
1
Oxygen [Φ( O )] in MeOH for 1-E, 4-E, and 5-E
2
λmax, nm ε, M− cm−1 λFL, nm
1
ΦFL
Φ( O )
1
cmpd
2
a
6.3 × 104
4.4 × 10
8.1 × 104
6.5 × 104
6.9 × 104
6.6 × 10
2.5 × 104
4.9 × 10
2.7 × 104
1
-S
571
581
601
641
658
670
575
689
610
700
633
675
587
603
0.44
0.21
0.87
0.43
0.15
0.65
0.31
<0.05
a
4
Spectral and Photophysical Properties of Dyes 4-E
and 5-E. The absorption spectra of the extended rhodamine
1-Se
0.009
b
1-Te
4-S
<0.005
dyes 4-E and 5-E in CH Cl are shown in Figure 1. Values of
715
717
0.47 ± 0.01
0.009 ± 0.001
<0.003
2
2
λmax in CH Cl , the molar extinction coefficient (ε) in CH Cl ,
4-Se
4-Te
5-S
2
2
2
2
4
the fluorescence emission maximum (λ ) in CH Cl , and the
FL
2
2
quantum yield for fluorescence (Φ ) in MeOH are compiled
775
781
0.18 ± 0.01
FL
4
in Table 2. For comparison purposes, the same parameters for
the tetramethylrosamines 1-E are included in Table 2 as well.
5-Se
5-Te
0.009 ± 0.001
<0.05
<0.05
−1
4
The dyes have a solubility of 1−2 mg mL in MeOH and
5.3 × 10
5.0 × 104
2.7 × 104
<0.003
CH Cl .
2
2
The chromophores associated with dyes 4-E and 5-E have
remarkably different wavelength distributions and bandwidths
as shown in Figure 1. The absorption spectra of “bent” dyes 4-E
have values of λmax for the major band that are 69−77 nm
longer than the corresponding 1-E analogue. Interestingly,
a
b
Reference 11. Reference 12.
aggregates with dyes related in structure to dyes 1-E has been
documented when the dyes bind to TiO2.
−1
16−18
bandwidths at half-height increase from 30 nm (670 cm ) for
As a cursory
−1
−1
4
4
-Te to 40 nm (920 cm ) for 4-Se to 50 nm (1210 cm ) for
-S (Figure 1a). One possibility for the varying bandwidths is
probe of aggregation, bandwidths at half-height were measured
over a range of concentrations (1 × 10− M to 2 × 10 M) and
6
−5
the formation of aggregates with 4-S and 4-Se. Formation of H-
remained constant.
E
DOI: 10.1021/acs.organomet.6b00255
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
The spectral broadening in solution is even greater for dyes
observed in the experimental spectra with the exception of the
high energy shoulder in the experimental spectra likely due to
the formation of H-aggregates in solution (Supporting
Information).
For the dyes 5-E, the lowest energy excitation is a
combination of two excitations, both having contributions
5
-E. The bandwidths at half-height for 5-S and 5-Se are ≥100
nm for the long-wavelength bands (λ of 689 and 700 nm,
max
respectively). As was observed with 4-Te, the band structure is
sharper in the spectrum of 5-Te relative to its lighter chalcogen
analogues 5-S and 5-Se. Values of λmax are ≈120 nm longer for
5
-S and 5-Se relative to 1-S and 1-Se, respectively. For 5-Te,
from the HOMO to LUMO and HOMO-1 to LUMO, (f =
1
the shorter 633 nm band has stronger absorbance at λmax than
the longer-wavelength 675 nm band. Both of these bands have
values of λmax at longer wavelengths than λmax for 1-Te (601
nm). Again, as a cursory probe of aggregation, relative
intensities of the various bands and bandwidths at half-height
0.43−0.12, f = 0.52−0.79, Table 4). As shown in Figure 3,
2
both HOMO and LUMO energies of the 5-E dyes are little
affected by the heavy chalcogen atom substitution even though
the chalcogen atom is contributing to both and the chalcogen
atom contribution increases as the size of the chalcogen
increases. The HOMO energy levels show a small increase in
energy as the chalcogen atom increases in size from −8.08 eV
for 5-O to −8.00 eV for 5-Te (Figure 3). The calculations also
show that nitrogen contributions remain fairly constant in both
HOMO and LUMO across the 5-E series.
−6
were measured over a range of concentrations (1 × 10 M to 2
−5
×
10 M) and remained constant.
Values of Φ were determined from steady-state fluo-
FL
rescence spectra for 4-S, 4-Se, 5-S, 5-Se, and 1-Se (reference
1
1
standard with Φ = 0.009) in MeOH with excitation at 532
FL
nm (Table 2). Neither 4-Te nor 5-Te gave a detectable
In contrast, the HOMO-1 increases in energy by 0.44 eV as
the chalcogen atom increases in size from −8.82 eV for 5-O to
−8.38 eV for 5-Te (Figure 3). The chalcogen contribution to
the HOMO-1 also increases with increasing size of the
chalcogen atom, but the most striking difference is in the
contribution from the two nitrogen atoms. In 5-O, the
naphthalene-like nitrogen does not contribute to the HOMO-
1. As the chalcogen atom contribution increases, the
contribution of the naphthalene-like nitrogen also increases in
the HOMO-1, which would increase the cyanine like character
of this orbital.
fluorescence and values of Φ were arbitrarily assigned to be
FL
<
Φ
0.003. Dye 4-S has Φ of 0.47, which is quite similar to the
FL
FL
of 0.44 for 1-S. Dyes 1-Se, 4-Se, and 5-Se have identical
vales of Φ of 0.009. Dye 5-S has Φ of 0.18, which is lower
FL
FL
than Φ for 1-S and 4-S. The Stokes shifts for 1-S and 1-Se as
FL
defined by the wavelength difference between λ and λFL are
max
16 and 22 nm, respectively. For 4-S, 4-Se, and 5-S, values of the
Stokes shift are larger at 74 nm for 4-S, 59 nm for 4-Se, 86 nm
for 5-S, and 81 nm for 5-Se.
1
1
Quantum yields for the generation of O [Φ( O )] by dyes
2
2
4
1
1
-E and 5-E were measured by time-resolved spectroscopy at
270 nm of O luminescence in air-saturated methanol using
-Se as a standard [Φ( O ) = 0.87]. Values of Φ( O ) for
bent” rhodamines 4-E were comparable to their 1-E analogue
as shown in Table 2. Values of Φ( O ) were determined to be
.15 for 4-S, 0.65 for 4-Se, and 0.31 for 4-Te. In contrast, the
linear” rhodamines 5-E generated O inefficiently with values
The overlap of the chalcogen atom with the carbon π-
framework can contribute to the spectral differences observed
between the 4-E and 5-E series. The broadening is observed in
the calculated spectra with two low energy transitions with
contributions from the HOMO-1 and HOMO to LUMO
(Supporting Information). For the tetramethylrosamines 1-E,
the relative contributions of anthracene-like resonance and
1
36
2
1
11
1
2
2
“
1
2
0
“
1
2
1
12
of Φ( O ) < 0.05 (Table 2).
cyanine-like resonance was a function of the chalcogen atom.
2
DFT Calculations. The structures of 4-E and 5-E were
optimized with DFT (B3LYP/6-311+G(d)/LanL2DZ). TD-
DFT calculations were carried out on the optimized structures
to analyze the electronic spectra of 4-E and 5-E. For all of the
dyes 4-E, the lowest energy excitation is due solely to the
HOMO−LUMO transition (f = 0.67−0.75, Table 3). No other
The anthracene-like contribution decreased as the chalcogen
atom increased in size. As shown in Chart 2, the dyes 4-E and
5-E each have a cyanine-like resonance contributing to the
chromophore as well as a benzanthracene-like resonance
(benz[a]anthracene for 4-E and benz[b]anthracene or
tetracene for 5-E). The benzanthracene contributions should
decrease as the chalcogen atom increases in size while the
cyanine contributions should increase. The calculations show
this trend in the HOMO-1 orbitals for the 5-E series with
increasing cyanine character and decreasing tetracene character
as the chalcogen atom increases in size. In the 4-E series, the
HOMO is essentially all cyanine in character with minimal
contribution from the chalcogen atom.
Table 3. Main Transitions, Oscillator Strengths (f), and
Wavelengths (λcalcd) Obtained by TD-DFT Calculations and
the Corresponding Observed Wavelengths (λ ) for Dyes 4-
obs
E
ex1
main transition
f
λcalcd (nm)
λobs (nm)
4
-O
HOMO → LUMO
HOMO → LUMO
HOMO → LUMO
HOMO → LUMO
0.7248
0.6981
0.6701
0.6765
522.7
550.2
560.8
570.0
4
4
4
-S
641
658
670
CONCLUSIONS
■
-Se
-Te
The extended chalcogenorhodamine dyes 4-E and 5-E have
been prepared with absorption maxima (λmax) > 630 nm. Dyes
5
-E absorb light strongly out to 700 nm. The 630−700 nm
orbitals contribute to the low energy absorption. As shown in
the frontier molecular orbitals (FMOs) of Figure 2, the HOMO
is very cyanine-like with a node on the chalcogen atom for the
optical window is important as it applies to photosensitizers for
PDT (where penetration of light in tissue increases in the 600−
800-nm window) and photosensitizers for the generation of
solar electricity (harvesting of solar near-infrared light). Key to
the synthesis of these chromophores is a highly regioselective
synthesis of chalcogenoxanthones 6-E and 7-E as the
precursors to the extended rhodamine dyes. The regioselective
generation of 1-lithio-6-dimethylamino-2-naphthamide 9 or 3-
lithio-6-dimethylamino-2-naphthamide 10 (Scheme 1) allowed
4
-E series. The energy of the HOMO is only slightly
destabilized with heavy chalcogen substitution. The LUMO
however is localized on the chalcogen atom and is stabilized
with the heavier chalcogen atoms Se and Te. This results in the
red-shifted electronic spectra as the size of the chalcogen atom
increases. The calculated absorption spectra follow the trends
F
DOI: 10.1021/acs.organomet.6b00255
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Figure 2. FMOs from DFT calculations for extended chalcogenorhodamine dyes 4-E (E = O, S, Se, Te).
Table 4. Main Transitions, % Contributions, Oscillator
Strengths (f), and Wavelengths (λcalcd) Obtained by TD-
DFT Calculations and Corresponding Observed
DSSCs. Like their 1-E analogues, the contributions of H- and/
or J-aggregation on TiO to the photoelectrical performance of
2
these dyes could then be evaluated.
Wavelengths (λ ) for Dyes 5-E
TD-DFT calculations show that the lowest energy absorption
for 4-E is from a HOMO to LUMO transition, and that the
energy of the LUMO is more dependent on the chalcogen
atom than the energy of the HOMO, which remains fairly
constant across the chalcogen series. This trend is reversed in
the 5-E series where the LUMO remains constant across the
chalcogen series and the energy of the HOMO is more
chalcogen dependent. Dyes 5-E have two low energy
absorptions, with contributions from the HOMO-1 to
LUMO transition as well as from the HOMO to LUMO
transition. The energy of the HOMO-1 to LUMO transition is
strongly dependent on the chalcogen atom. These two
absorptions cause the broad peak in the experimental
absorption spectra.
obs
main transitions
%
λcalcd
(nm)
λobs
(nm)
cmpd
from
HOMO-1 LUMO
HOMO LUMO
to
contribution
f
5-O
11.5
87.2
3.1
0.4275
589.0
HOMO-2 LUMO
HOMO-1 LUMO
0.5225
470.4
83.3
11.7
15.2
83.4
82.3
14.7
18.5
80.4
79.7
17.9
21.3
77.9
77.3
20.6
HOMO
HOMO-1 LUMO
HOMO LUMO
HOMO-1 LUMO
HOMO LUMO
-Se HOMO-1 LUMO
HOMO LUMO
HOMO-1 LUMO
HOMO LUMO
-Te HOMO-1 LUMO
HOMO LUMO
HOMO-1 LUMO
HOMO LUMO
LUMO
5
5
5
-S
0.3035
0.5978
0.2585
0.6686
0.173
609.9
496.1
619.9
507.9
644.7
523.4
680
575
700
610
675
633
EXPERIMENTAL SECTION
■
37
Methyl 6-(Dimethylamino)-2-naphthoate (12).
Iodome-
thane (12.0 mL, 192 mmol) was added dropwise to a stirred solution
of 6-amino-2-naphthoic acid (4.50 g, 24.0 mmol) and sodium
carbonate (15.3 g, 144 mmol) in DMF (200 mL). The resulting
mixture was heated at 110 °C for 16 h before being cooled to 60 °C
and DABCO (4.05 g, 36.0 mmol) added. Heating was then resumed at
0.7904
1
00 °C for 4 h. After cooling to ambient temperature, water (150 mL)
was added and the product was extracted with diethyl ether (3 × 50
the selective preparation of 6-E and 7-E, respectively.
Increasing steric bulk in the naphthamide alkyl groups gave
highly regioselective metalation of diisopropyl naphthamide
mL). The combined organic extracts were washed with water (3 × 100
mL), dried over anhydrous MgSO , and concentrated. The crude
4
product was recrystallized from CH Cl /hexanes to give 5.46 g (99%)
2
2
11b at the 1-position with n-BuLi/TMEDA. Increasing steric
37
of 12 as a brown solid, mp 150−152 °C (literature mp 148−149
C): H NMR (500 MHz, CDCl ) δ 8.44 (s, 1 H), 7.93 (dd, 1 H, J =
.5, 9.0 Hz), 7.79 (d, 1 H, J = 9.0 Hz), 7.63 (d, 1 H, J = 9.0 Hz), 7.17
(dd, 1 H, J = 2.5, 9.5 Hz), 6.88 (d, 1 H, J = 2.5 Hz), 3.94 (s, 3 H), 3.10
(s, 6 H); 13C NMR (75.5 MHz, CDCl
) δ 167.6, 150.0, 137.5, 130.9,
130.3, 125.9, 125.7, 125.2, 123.0, 116.2, 105.3, 51.8, 40.4; IR (film on
bulk in a lithium dialkylamide gave highly regioselective
metalation of diethyl naphthamide 11a at the 3-position with
LiTMP.
The solution absorption spectra of both the “bent” extended
rhodamines 4-E and the “linear” extended rhodamines 5-E
suggest that the chalcogen atom impacts the spectra through
the effectiveness of overlap with the carbon π-framework. As
the size of the chalcogen atom increases, benzanthracene-like
resonance contributions decrease while cyanine-like contribu-
tions increase. The incorporation of aryl or heteroaryl groups
1
°
1
3
3
−1
NaCl) 2949, 1714, 1624, 1508, 1436, 1384, 1290 cm ; HRMS (ESI,
HRDFMagSec) m/z 230.1174 (calcd for C H NO + H : 230.1176).
+
14
15
2
N,N-Diethyl 2-(6-Dimethylamino)naphthamide (11a). n-Bu-
tyllithium (1.25 M, 8.37 mL, 10.5 mmol) was added dropwise to a
stirred solution of diethylamine (1.17 mL, 11.3 mmol) in THF (30
mL) at −78 °C. The resulting mixture was stirred for 1 h and then
transferred to a stirred solution of 12 (2.0 g, 8.72 mmol) in THF (50
mL) at ambient temperature. The resulting solution was heated at 45
°C for 30 min and then cooled to ambient temperature. A solution of
bearing functionality for anchoring to TiO or other semi-
2
1
6−18
conductors
in extended rhodamines 4-E and 5-E would
generate extended rhodamine dyes that could be evaluated in
G
DOI: 10.1021/acs.organomet.6b00255
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Figure 3. FMOs from DFT calculations for extended chalcogenorhodamine dyes 5-E (E = O, S, Se, Te).
1
1
1
71.5, 149.0, 134.8, 132.3, 129.0, 126.1, 125.8, 124.8, 123.9, 116.7,
Chart 2. Cyanine and Benzanthracene Resonance
Contributions to the π-Systems of Dyes 4-E and 5-E
05.9, 47.5 (br), 40.6, 20.8. IR (film on NaCl) 2968, 2927, 1627, 1505,
−1
436, 1378, 1335 cm ; HRMS (EI, HRDFMagSec) m/z 298.2047
(
calcd for C H N O: 298.2040).
19 26 2
General Procedure for Metalation of Naphthamide 11a with
s-BuLi and Quenching with Dichalcogenides 8-E. s-Butyllithium
0.87 M, 4.46 mL, 3.88 mmol) was added dropwise to a stirred
(
solution of naphthamide 11a (1.0 g, 3.70 mmol) and TMEDA (606
μL, 4.07 mmol) in THF (75 mL) at −78 °C. A solution of disulfide 8-
2
2
22
29
S
(2.25 g, 7.39 mmol), 8-Se (2.94 g, 7.39 mmol), or 8-Te (3.66
g, 7.39 mmol) in THF (30 mL) at −78 °C was immediately added,
and the resulting mixture was stirred at −78 °C for 3 h and then
warmed to ambient temperature with stirring overnight (12 h). A
solution of saturated NH Cl (50 mL) was added, and products were
saturated NH Cl (50 mL) was added, and products were extracted
4
4
extracted with CH Cl (3 × 150 mL). The combined organic extracts
with CH Cl (3 × 150 mL). The combined organic extracts were dried
2
2
2
2
were dried over anhydrous MgSO4 and concentrated. The crude
products were purified via chromatography on SiO eluted with 0.5:9.5
Et O/CH Cl (R = 0.5) to give 1.43 g (91%) of a mixture of 15-S and
over anhydrous MgSO and concentrated. The crude product was
4
recrystallized from CH Cl /hexanes to give 2.29 g (97%) of 11a as a
2
2
2
yellow solid, mp 99−100 °C. Purity was assessed by NMR
2
2
2
f
1
spectroscopy: H NMR (500 MHz, CDCl ) δ 7.72 (s, 1 H), 7.71
16-S, 1.61 g (93%) of a mixture of 15-Se and 16-Se, and 1.74 g (91%)
3
(
8
d, 1 H, J = 9.0 Hz), 7.65 (d, 1 H, J = 8.5 Hz), 7.37 (dd, 1 H, J = 2.0,
of a mixture of 15-Te and 16-Te. These mixtures were used without
1
.5 Hz), 7.18 (dd, 1 H, J = 2.5, 9.0 Hz), 6.90 (d, 1 H, J = 2.5 Hz),
further purification or separation. H NMR spectra of mixtures are in
13
3
.69−3.26 (m, 4 H), 3.07 (s, 6 H), 1.40−1.06 (m, 6 H); C NMR
the Supporting Information. For 15-S/16-S: HRMS (EI, HRDFMag-
(
75.5 MHz, CDCl ) δ 171.5, 148.8, 134.9, 130.1, 128.8, 125.8, 125.5,
Sec) m/z 421.2182 (calcd for C25
H N OS: 421.2182). For 15-Se/16-
31 3
3
1
2
25.4, 124.2, 116.4, 105.4, 43.3, 40.2, 39.1, 13.4; IR (film on NaCl)
Se: HRMS (ESI, HRDFMagSec) m/z 470.1690 (calcd for
−1
80
+
970, 2890, 2750, 1627, 1506, 1420, 1382 cm ; HRMS (ESI,
C H N O Se + H : 470.1705. For 15-Te/16-Te: HRMS (ESI,
25 31 3
+
130
+
HRDFMagSec) m/z 271.1805 (calcd for C H N O + H : 271.1805).
HRDFMagSec) m/z 520.1688 (calcd for C25H N O Te + H :
31 3
17
22
2
N,N-Diisopropyl 2-(6-Dimethylamino)naphthamide (11b). n-
Butyllithium (1.25 M, 4.89 mL, 6.11 mmol) was added dropwise to a
stirred solution of diisopropylamine (978 μL, 6.98 mmol) in THF (15
mL) at −78 °C. The resulting mixture was stirred for 1 h then
transferred to a stirred solution of 12 (1.0 g, 4.36 mmol) in THF (20
mL) at ambient temperature. The resulting solution was heated at 45
520.1602).
N,N-Diethyl Naphthamide 16-S. n-Butyllithium (2.00 M, 2.77
mL, 5.55 mmol) was added dropwise to a stirred solution of 2,2,6,6-
tetramethylpiperidine (1.03 mL, 6.10 mmol) in THF (20 mL) at 0 °C.
The resulting mixture was stirred for 15 min then transferred to a
stirred solution of naphthamide 11a (500 mg, 1.85 mmol) in THF (20
mL) at −78 °C. The resulting solution was stirred at −78 °C for 1.5 h
°
C for 30 min and then cooled to ambient temperature. A solution of
2
2
saturated NH Cl (50 mL) was added, and products were extracted
and a solution of disulfide 8-S (1.69 g, 5.55 mmol) in THF (30 mL)
at −78 °C was added. The resulting mixture was stirred at −78 °C for
3.5 h and then 12 h at ambient temperature. A solution of saturated
4
with CH Cl (3 × 150 mL). The combined organic extracts were dried
2
2
over anhydrous MgSO and concentrated. The crude product was
4
recrystallized from CH Cl /hexanes to give 1.10 g (85%) of 11b as an
NH Cl (50 mL) was added and products extracted with CH Cl (3 ×
4 2 2
150 mL). The combined organic extracts were dried over anhydrous
2
2
orange solid, mp 148−150 °C. Purity was assessed by NMR
1
spectroscopy: H NMR (500 MHz, CDCl ) δ 7.70 (d, 1 H, J = 9.5
MgSO and concentrated. The crude product was purified via gradient
3
4
Hz), 7.65 (s, 1 H), 7.64 (d, 1 H, J = 8.0 Hz), 7.31 (dd, 1 H, J = 2.0, 9.0
Hz), 7.18 (dd, 1 H, J = 3.0, 9.5), 6.90 (d, 1 H, J = 3.0 Hz), 3.77 (br s, 2
column chromatography on SiO (1:4 EtOAc/hexanes to 1:1 EtOAc/
2
hexanes) to give 429 mg (55%) of 16-S as a yellow oil (91% based on
H), 3.06 (s, 6 H), 1.37 (br s, 12 H); 13C NMR (75.5 MHz, CDCl ) δ
recovered 11a). Purity was assessed by NMR spectroscopy: H NMR
1
3
H
DOI: 10.1021/acs.organomet.6b00255
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
+
(
300 MHz, CD Cl ) δ 7.65 (d, 1 H, J = 8.7 Hz), 7.51 (s, 1 H), 7.45 (s,
HRDFMagSec) m/z 450.2556 (calcd for C H N OS + H :
27 35 3
2
2
1
1
3
1
H), 7.18 (t, 1 H, J = 8.4 Hz), 7.14 (dd, 1 H, J = 3.0, 8.7 Hz), 6.85 (s,
H), 6.74 (d, 1 H, J = 7 Hz), 6.70 (s, 1 H), 6.67 (d, 1 H, J = 8.5 Hz),
.71−3.50 (m, 2 H), 3.31−3.18 (m, 2 H), 3.02 (s, 6 H), 2.94 (s, 6 H),
.32 (t, 3 H, J = 6.9 Hz), 1.10 (t, 3 H, J = 6.9 Hz); 13C NMR (75.5
450.2574).
N,N-Diisopropyl Naphthamide 19-Se. n-Butyllithium (1.95 M,
567 μL, 1.10 mmol), naphthamide 11b (300 mg, 1.00 mmol),
TMEDA (165 μL, 1.10 mmol), and diselenide 8-Se (440 mg, 1.10
22
MHz, CD Cl ) δ 169.4, 151.5, 149.6, 135.5, 135.2, 132.7, 131.9, 130.0,
mmol) in THF were treated as described for the preparation of 19-S.
The crude product was purified via column chromatography on SiO2
(1:9 Et O/CH Cl , R = 0.4) followed by recrystallization out of
2
2
1
4
1
28.8, 128.3, 125.5, 124.9, 120.3, 116.8, 116.3, 112.0, 105.1, 43.3, 40.6,
0.5, 39.2, 14.2, 12.9; IR (film on NaCl) 2972, 2930, 2820, 1623, 1589,
503, 1444, 1382 cm ; HRMS (EI, HRDFMagSec) m/z 421.2182
2
2
2
f
−1
CH CN to give 387 mg (82%) of 19-Se (94% based on recovered
3
(
calcd for C H N OS: 421.2182).
N,N-Diethyl Naphthamide 16-Se. n-Butyllithium (2.22 M, 2.50
11b) as a yellow solid, mp 178−179 °C. Purity was assessed by NMR
25
31
3
1
spectroscopy: H NMR (500 MHz, CDCl ) δ 8.25 (d, 1 H, J = 9.0
3
mL, 5.55 mmol), 2,2,6,6-tetramethylpiperidine (1.03 mL, 6.10 mmol),
naphthamide 11a (500 mg, 1.85 mmol), and diselenide 8-Se (2.21 g,
Hz), 7.71 (d, 1 H, J = 8.5 Hz), 7.23 (d, 1 H, J = 8.5 Hz), 7.12 (dd, 1 H,
J = 2.5, 9.0 Hz), 6.91 (t, 1 H, J = 8.0 Hz), 6.88 (d, 1 H, J = 2.5 Hz),
6.70 (s, 1 H), 6.46−6.41 (m, 2 H), 3.74 (septet, 1 H, J = 6.5 Hz), 3.48
(septet, 1 H, J = 7.0 Hz), 3.03 (s, 6 H), 2.80 (s, 6 H), 1.61 (d, 3 H, J =
6.5 Hz), 1.59 (d, 3 H, J = 7.0 Hz), 1.05 (d, 3 H, J = 6.5 Hz), 0.911 (d,
3 H, J = 7.0 Hz); 13C NMR (75.5 MHz, CD Cl ) δ 170.3, 151.4,
2
2
5
1
.55 mmol) in THF were treated as described for the preparation of
6-S. The crude product was purified via gradient column
chromatography (SiO , 1:4 EtOAc/hexanes to 1:1 EtOAc/hexanes)
2
to give 436 mg (50%) of 16-Se as a yellow oil (94% based on
2
2
1
recovered 11a). Purity was assessed by NMR spectroscopy: H NMR
149.2, 140.7, 135.5, 134.2, 130.1, 129.6, 129.2, 127.9, 123.6, 123.4,
118.0, 117.6, 113.9, 110.5, 106.6, 51.3, 46.0, 40.6, 40.4, 20.9, 20.8, 20.7,
20.5; IR (film on NaCl) 2967, 2938, 1618, 1588, 1497, 1445, 1368,
(
500 MHz, CD Cl ) δ 7.72−7.64 (m, 2 H), 7.57 (s, 1 H), 7.20 (t, 1 H,
2
2
J = 8.0 Hz), 7.14 (d, 1 H, J = 3.5 Hz), 7.05 (s, 1 H), 6.94 (d, 1 H, J =
−1
7
.5 Hz), 6.76−6.68 (m, 2 H), 3.71−3.58 (m, 2 H), 3.36−3.24 (m, 2
1331 cm ; HRMS (ESI, HRDFMagSec) m/z 498.2020 (calcd for
80
+
H), 3.00 (s, 6 H), 2.94 (s, 6 H), 1.44−1.30 (m, 3 H), 1.20−1.08 (m, 3
C H N O Se + H : 498.2018).
27 35 3
H); 13C NMR (75.5 MHz, CD Cl ) δ 170.1, 151.6, 149.6, 135.8,
N,N-Diisopropyl Naphthamide 19-Te. n-Butyllithium (1.95 M,
476 μL), naphthamide 11b (250 mg, 0.838 mmol), TMEDA (250 mg,
2
2
1
1
2
33.3, 131.0, 130.1, 130.0, 128.9, 128.2, 125.2, 124.9, 122.4, 118.4,
2
9
16.8, 112.2, 105.0, 43.5, 40.7, 40.5, 39.3, 14.4, 12.9; IR (film on NaCl)
0.838 mmol), and ditelluride 8-Te (457 mg, 0.921 mmol) in THF
were treated as described for the preparation of 19-S. The crude
product was purified via column chromatography on SiO (1:9 Et O/
−1
990, 2930, 2800, 1622, 1588, 1498, 1444, 1381 cm ; HRMS (ESI,
80
+
HRDFMagSec) m/z 470.1690 (calcd for C H N O Se + H :
25
31
3
2
2
4
70.1705).
N,N-Diethyl Naphthamide 16-Te. n-Butyllithium (2.22 M, 1.39
mL, 2.77 mmol), 2,2,6,6-tetramethylpiperidine (515 μL, 3.05 mmol),
CH Cl , R = 0.4) followed by recrystallization from CH CN to give
2
2
f
3
429 mg (94%) of 19-Te as a yellow solid, mp 184−185 °C. Purity was
1
assessed by NMR spectroscopy: H NMR (500 MHz, CDCl ) δ 8.22
3
29
1
1a (250 mg, 0.925 mmol), and ditelluride 8-Te (1.37 g, 2.77 mmol)
(d, 1 H, J = 9.5 Hz), 7.70 (d, 1 H, J = 8.0 Hz), 7.21 (d, 1 H, J = 8.5
Hz), 7.08 (dd, 1 H, J = 3.0, 9.5 Hz), 6.90−6.83 (m, 2 H), 6.79 (s, 1
H), 6.59 (d, 1 H, J = 8.0 Hz), 6.46 (dd, 1 H, J = 2.5, 8.5 Hz), 3.83
(septet, 1 H, J = 7.0 Hz), 3.49 (septet, 1 H, J = 6.5 Hz), 3.03 (s, 6 H),
2.77 (s, 6 H), 1.64 (d, 3 H, J = 7.0 Hz), 1.59 (d, 3 H, J = 7.0 Hz), 1.09
in THF were treated as described for the preparation of 16-S. The
crude product was purified via gradient column chromatography
(
(
SiO , 1:4 EtOAc/hexanes to 1:1 EtOAc/hexanes) to give 254 mg
53%) of 16-Te as a yellow oil (92% based on recovered 11a). Purity
2
1
13
was assessed by NMR spectroscopy: H NMR (300 MHz, CD Cl ) δ
(d, 3 H, J = 6.5 Hz), 0.976 (d, 3 H, J = 6.5 Hz); C NMR (125.5
2
2
7.82 (s, 1 H), 7.68 (d, 1 H, J = 9.3 Hz), 7.62 (s, 1 H), 7.37 (d, 1 H, J =
MHz, CDCl ) δ 171.8, 150.7, 148.5, 143.3, 134.6, 134.0, 129.4, 128.9,
3
1
.8 Hz), 7.28 (d, 1 H, J = 6.9 Hz), 7.16 (t, 1 H, J = 8.4 Hz), 7.13 (dd, 1
128.8, 122.7, 122.5, 118.3, 117.3, 117.2, 113.2, 110.7, 106.1, 51.0, 45.6,
H, J = 2.4, 8.7 Hz), 6.76 (dd, 1 H, J = 2.4, 8.4 Hz), 6.64 (d, 1 H, J =
.4), 3.66−3.40 (m, 4 H), 3.00 (s, 6 H), 2.95 (s, 6 H), 1.41−1.18 (m, 6
40.3, 40.0, 20.6, 20.5, 20.2, 20.1; IR (film on NaCl) 2968, 2929, 2802,
−
1
2
1620, 1584, 1496, 1444, 1367, 1338 cm ; HRMS (ESI,
13
130
+
H); C NMR (75.5 MHz, CD Cl ) δ 171.9, 151.5, 149.5, 136.2,
HRDFMagSec) m/z 548.1912 (calcd for C H N O Te + H :
2
2
27 35 3
1
1
2
34.0, 133.8, 130.1, 129.1, 128.0, 125.1, 124.6, 124.0, 116.7, 116.6,
548.1915).
15.5, 112.6, 104.7, 40.6, 40.5, 40.4, 13.8; IR (film on NaCl) 2970,
Preparation of Ketones 17 and 18. n-Butyllithium (2.22 M, 458
μL, 1.02 mmol) was added dropwise to a stirred solution of
naphthamide 11a (250 mg, 0.925 mmol) and TMEDA (152 μL,
1.02 mmol) in THF (20 mL) at −78 °C. The resulting mixture was
−1
940, 2900, 1619, 1582, 1502, 1443, 1420, 1382 cm ; HRMS (ESI,
1
30
+
HRDFMagSec) m/z 520.1602 (calcd for C H ON Te + H :
25
31
3
520.1602).
22
N,N-Diisopropyl Naphthamide 19-S. n-Butyllithium (2.05 M,
stirred for 1 min before adding a solution of diselenide 8-Se (405 mg,
1.02 mmol) in THF (20 mL) at −78 °C with continued stirring at
−78 °C for 3 h and then 15 h at ambient temperature. A solution of
450 μL, 0.838 mmol) was added dropwise to a stirred solution of
naphthamide 11b (250 mg, 0.921 mmol) and TMEDA (137 μL, 0.921
mmol) in THF (20 mL) at −78 °C. The resulting mixture was stirred
saturated NH Cl (50 mL) was added, and products were extracted
4
22
for 30 min before adding a solution of disulfide 8-S (281 mg, 0.921
mmol) in THF (20 mL) at −78 °C. The resulting mixture was stirred
at −78 °C for 3 h and then 15 h at ambient temperature. A solution of
with CH Cl (3 × 150 mL). The combined organic extracts were dried
2
2
over anhydrous MgSO and concentrated. The crude product was
4
purified via column chromatography on SiO (1:4 EtOAc/hexanes, R
= 0.5 and 0.9) to give 94 mg (40%) of 17 as a brown solid, mp 80−81
°C, and 126 mg (30%) of 18 as a dark orange oil. Purity was assessed
by NMR spectroscopy.
For 17: H NMR (500 MHz, CDCl ) δ 8.33 (d, 1 H, J = 2.0 Hz),
2
f
saturated NH Cl (50 mL) was added, and products were extracted
4
with CH Cl (3 × 150 mL). The combined organic extracts were dried
over anhydrous MgSO and concentrated. The crude product was
purified via column chromatography (SiO , 1:9 Et O/CH Cl , R =
2
2
4
1
2
2
2
2
f
3
0
.4) followed by recrystallization from CH CN to give 302 mg (80%)
7.93 (dd, 1 H, J = 2.0, 9.0 Hz), 7.80 (d, 1 H, J = 9.5 Hz), 7.64 (d, 1 H,
J = 8.5 Hz), 7.17 (dd, 1 H, J = 2.5, 9.0 Hz), 6.88 (d, 1 H, J = 2.5 Hz),
3.11 (s, 6 H), 3.04 (t, 2 H, J = 7.5 Hz), 1.77 (quintet, 2 H, J = 7.0 Hz),
3
of 19-S (89% based on recovered 11b) as a yellow solid, mp 174−175
1
°
C. Purity was assessed by NMR spectroscopy: H NMR (500 MHz,
CD Cl) δ 8.24 (d, 1 H, J = 9.0 Hz), 7.72 (d, 1 H, J = 8.5 Hz), 7.24 (d,
1
3
1.45 (sextet, 2 H, J = 7.5 Hz), 0.975 (t, 3 H, J = 7.0 Hz); C NMR
3
1
H, J = 8.0 Hz), 7.14 (dd, 1 H, J = 9.5, 3.0 Hz), 6.94 (t, 1 H, J = 8.5
(75.5 MHz, CDCl ) δ 200.0, 150.0, 137.5, 130.5, 130.4, 129.7, 126.0,
3
Hz), 6.89 (d, 1 H, J = 2.5 Hz), 6.62 (s, 1 H), 6.41 (dd, 1 H, J = 8.0, 2.5
Hz), 6.34 (d, 1 H, J = 8.5 Hz), 3.70 (septet, 1 H, J = 6.5 Hz), 3.48
124.9, 124.5, 116.1, 105.1, 40.2, 37.9, 26.8, 22.5, 13.9; IR (film on
−1
NaCl) 2951, 2918, 2850, 1654, 1616, 1506, 1383, 1340 cm ; HRMS
+
(
septet, 1 H, J = 7.0 Hz), 3.03 (s, 6 H), 2.81 (s, 6 H), 1.62−1.57 (m, 6
(ESI, HRDFMagSec) m/z 256.1689 (calcd for C H NO + H :
17
21
13
H), 1.05 (d, 3 H, J = 6.5 Hz), 0.92 (d, 3 H, J = 7.0 Hz); C NMR
75.5 MHz, CD Cl) δ 169.5, 150.6, 148.6, 139.5, 138.6, 135.1, 129.1,
256.1696). 1
(
For 18: H NMR (500 MHz, CDCl ) δ 8.07 (d, 1 H, J = 1.5 Hz),
3
3
1
5
1
28.8, 127.6, 127.4, 124.5, 123.4, 117.3, 115.4, 111.1, 109.5, 106.2,
7.94 (dd, 1 H, J = 1.5, 9.0 Hz), 7.64−7.58 (m, 2 H), 7.11−7.15 (m, 2
H), 6.93 (d, 1 H, J = 7.5 Hz), 6.85 (d, 1 H, J = 2.5 Hz), 6.79 (s, 1 H),
6.65 (dd, 1 H, J = 2.0, 8.0 Hz), 4.69 (dd, 1 H, J = 1.0, 7.0 Hz), 3.09 (s,
0.8, 45.6, 40.3, 40.2, 20.7, 20.6, 20.2; IR (film on NaCl) 2967, 2814,
−
1
619, 1588, 1499, 1445, 1369, 1335 cm ; HRMS (ESI,
I
DOI: 10.1021/acs.organomet.6b00255
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
1
6
1
H), 2.80 (s, 6 H), 2.28−2.19 (m, 1 H), 2.07−1.98 (m, 1 H), 1.66−
spectroscopy: H NMR (500 MHz, CDCl ) δ 8.62−8.56 (m, 2 H),
3
13
.57 (m, 1 H), 1.56−1.48 (m, 1 H), 0.989 (t, 3 H, J = 7.0 Hz);
C
7.61−7.54 (m, 2 H), 7.17 (dd, 1 H, J = 2.5, 9.0 Hz), 6.90 (d, 1 H, J =
2.5 Hz), 6.87 (d, 1 H, J = 2.5 Hz), 6.79 (dd, 1 H, J = 2.5, 9.0 Hz), 3.11
NMR (75.5 MHz, CDCl ) δ 196.3, 150.5, 150.1, 137.4, 130.7, 130.1,
3
1
1
1
29.7, 129.3, 129.1, 125.9, 125.0, 124.9, 123.5, 119.9, 115.9, 112.5,
05.1, 46.2, 40.3, 40.1, 33.8, 21.5, 13.9; IR (film on NaCl) 2956, 2928,
657, 1619, 1588, 1494, 1444, 1384, 1348 cm ; HRMS (ESI,
(s, 6 H), 3.09 (s, 6 H); 13C NMR (75.5 MHz, CDCl ) δ 185.1, 151.6,
3
150.1, 136.2, 133.7, 130.2, 129.3, 128.5, 126.1, 125.5, 125.2, 123.0,
121.2, 115.6, 113.5, 112.4, 106.4, 40.3, 39.9; IR (film on NaCl) 2922,
1602, 1574, 1506, 1438, 1402, 1365, 1314 cm ; HRMS (ESI,
HRDFMagSec) m/z 447.0713 (calcd for C H N O Te + H :
−1
80
+
−1
HRDFMagSec) m/z 455.1598 (calcd for C H N O Se + H :
25
30
2
1
30
+
4
55.1596).
Diaryl Selenide 21-Se. Selenide 19-Se (200 mg, 0.403 mmol) was
dissolved in CF SO H (5 mL) and the resulting mixture heated at 135
21 20 2
447.0711).
Extended Thioxanthone 7-S. Phosphorus oxychloride (1.14 mL,
3
3
°
C for 48 h. The reaction mixture was cooled to 0 °C and carefully
12.2 mmol) was added dropwise to a solution of Et N (1.79 mL, 12.2
3
diluted with cold distilled water (25 mL). Cold 1 M NaOH was added
until the reaction mixture was basic (pH ≈ 10). The resulting mixture
was stirred for 6 h and products were extracted with CH Cl (3 × 250
mmol) and 16-S (429 mg, 1.02 mmol) in CH CN (25 mL). The
3
resulting mixture was heated at reflux for 12 h and then cooled to 0 °C.
A solution of 1 M NaOH (10 mL) was added slowly, and the resulting
mixture was poured into a stirred solution of cold 1 M NaOH (200
mL), stirred for 6 h, and products were extracted with CH Cl (3 ×
2
2
mL). The combined organic extracts were dried over anhydrous
MgSO and concentrated. The crude product was purified via column
chromatography on SiO (1:9 Et O/CH Cl , R = 0.3) followed by
4
2
2
250 mL). The combined organic extracts were dried over anhydrous
2
2
2
2
f
recrystallization from CH Cl /hexanes to give 112 mg (61%) of 21-Se
MgSO and concentrated. The resulting solid was recrystallized from
2
2
4
as a yellow solid, mp 124−125 °C. Purity was assessed by NMR
CH Cl /hexanes to give 294 mg (83%) of 7-S as an orange solid, mp
2
2
1
1
spectroscopy: H NMR (300 MHz, CDCl ) δ 8.46 (d, 1 H, J = 9.3
>250 °C. Purity was assessed by NMR spectroscopy: H NMR (500
3
Hz), 7.73 (d, 1 H, J = 8.1 Hz), 7.52 (d, 1 H, J = 8.4 Hz), 7.16 (dd, 1 H,
J = 2.7, 9.3 Hz), 6.94 (t, 1 H, J = 8.1 Hz), 6.87 (d, 1 H, J = 2.1 Hz),
MHz, CDCl ) δ 8.97 (s, 1 H), 8.46 (d, 1 H, J = 9.0 Hz), 7.89 (d, 1 H, J
3
= 9.5 Hz), 7.68 (s, 1 H), 7.16 (dd, 1 H, J = 2.5, 9.0 Hz), 6.60−6.80 (m,
2 H), 6.60 (m, 1 H); 3.12 (s, 6 H), 3.11 (s, 6 H); 1 C NMR (75.5
3
6
5
.59 (s, 1 H), 6.45 (dd, 1 H, J = 2.4, 8.4 Hz), 6.31 (d, 1 H, J = 7.5 Hz),
.75 (d, 1 H, J = 7.8 Hz), 4.28−4.12 (m, 1 H), 3.06 (s, 6 H), 2.80 (s, 6
MHz, CDCl ) δ 179.4, 152.3, 150.3, 139.7, 136.6, 132.6, 131.5, 131.1,
3
13
H), 1.08 (d, 6 H, J = 6.3 Hz); C NMR (75.5 MHz, CDCl ) δ 169.4,
130.6, 124.8, 123.9, 120.3, 118.6, 116.3, 110.9, 105.1, 102.9, 40.4, 40.1;
3
1
1
51.1, 149.0, 138.7, 135.9, 134.8, 130.6, 129.8, 128.7, 128.1, 125.6,
IR (film on NaCl) 1613, 1591, 1500, 1441, 1389, 1371, 1336, 1286
−
1
23.4, 117.4, 116.4, 112.3, 110.2, 106.0, 42.0, 40.4, 40.3, 22.3; IR (film
cm ; HRMS (ESI, HRDFMagSec) m/z 349.1369 (calcd for
−1
+
on NaCl) 3259, 2968, 1617, 1587, 1497, 1443, 1367, 1254 cm ;
HRMS (ESI, HRDFMagSec) m/z 456.1561 (calcd for C H N O Se
C
21
H
20
N
2
OS + H : 349.1370).
Extended Selenoxanthone 7-Se. Phosphorus oxychloride (931
μL, 9.99 mmol), Et N (1.39 mL, 9.99 mmol) and 16-Se (390 mg,
0.832 mmol) in CH CN (25 mL) were treated as described for the
preparation of 7-S. The resulting solid was recrystallized from
CH Cl /hexanes to give 247 mg (72%) of 7-Se as an orange solid,
mp >250 °C. Purity was assessed by NMR spectroscopy: H NMR
(500 MHz, CDCl ) δ 9.02 (s, 1 H), 8.50 (d, 1 H, J = 9.0 Hz), 7.87 (d,
80
24
29
3
+
+
H : 456.1559).
Extended Thioxanthone 6-S. Diaryl sulfide 19-S (162 mg, 0.360
mmol) was dissolved in CF SO H (3 mL) and the resulting mixture
3
3
3
3
heated at 140 °C for 72 h. The reaction mixture was cooled to 0 °C
and carefully diluted with cold distilled water (25 mL). Cold 1 M
NaOH was added until the reaction mixture was basic (pH ≈ 10). The
resulting mixture was stirred for 6 h, and products were extracted with
CH Cl (3 × 250 mL). The combined organic extracts were dried over
2
2
1
3
1 H, J = 9.0 Hz), 7.75 (s, 1 H), 7.15 (dd, 1 H, J = 2.5, 9.0 Hz), 6.78−
6.72 (m, 2 H), 6.69 (s, 1 H, J = 3.0 Hz), 3.11 (s, 6 H), 3.09 (s, 6 H);
2
2
13
anhydrous MgSO and concentrated. The crude product was purified
C NMR (75.5 MHz, CDCl ) δ 181.3, 152.2, 150.3, 136.8, 136.7,
3
4
via column chromatography on SiO (1:9 Et O/CH Cl , R = 0.7)
132.8, 132.0, 131.2, 129.5, 125.2, 125.0, 123.0, 120.2, 116.2, 111.1,
2
2
2
2
f
followed by recrystallization from CH Cl /hexanes to give 79 mg
107.9, 102.8, 40.4, 40.0; IR (film on NaCl) 2949, 1610, 1588, 1498,
2
2
−1
(
56%) of 6-S as a yellow solid, mp >260 °C. Purity was assessed by
1438, 1389, 1328 cm ; HRMS (EI, HRDFMagSec) m/z 396.0733
1
80
+
NMR spectroscopy: H NMR (500 MHz, CDCl ) δ 8.46−8.50 (m, 2
H), 8.20 (d, 1 H, J = 9.5 Hz), 7.59 (d, 1 H, J = 9.0 Hz), 7.18 (dd, 1 H,
J = 2.5, 9.0 Hz), 6.90 (d, 1 H, J = 2.5 Hz), 6.85 (dd, 1 H, J = 2.5, 9.5
Hz), 6.73 (d, 1 H, J = 2.0 Hz), 3.16−3.09 (m, 12 H); C NMR (75.5
MHz, CDCl ) δ 178.8, 151.9, 150.2, 138.2, 136.6, 136.2, 130.8, 125.3,
(calcd for C H N O Se : 396.0735).
3
21 20 2
Extended Telluroxanthone 7-Te. Phosphorus oxychloride (748
μL, 8.03 mmol), Et N (1.12 mL, 8.03 mmol) and 16-Te (346 mg,
3
13
0.669 mmol) in CH CN (25 mL) were treated as described for the
3
preparation of 7-S. The resulting solid was recrystallized from
CH Cl /hexanes to give 238 mg (80%) of 7-Te as an orange solid,
3
1
24.8, 124.5, 124.4, 120.9, 118.9, 115.3, 112.0, 106.6, 105.4, 40.3, 40.0;
2
2
−1
1
IR (film on NaCl) 2925, 1614, 1587, 1507, 1406, 1370, 1335 cm ;
HRMS (EI, HRDFMagSec) m/z 348.1291 (calcd for C H N OS :
mp >250 °C. Purity was assessed by NMR spectroscopy: H NMR
(500 MHz, CDCl ) δ 9.05 (s, 1 H), 8.52 (d, 1 H, J = 9.5 Hz), 7.87 (s,
+
21
20
2
3
3
48.1291).
1 H), 7.85 (d, 1 H, J = 9.5 Hz), 7.14 (dd, 1 H, J = 2.5, 9.5 Hz), 6.81 (d,
1 H, J = 2.5 Hz), 6.72 (dd, 1 H, J = 2.5, 9.0 Hz), 6.68 (d, 1 H, J = 2.0
Extended Selenoxanthone 6-Se. Diaryl selenide 19-Se (150 mg,
.302 mmol) and CF SO H (3 mL) were treated as described for the
Hz), 3.10 (s, 6 H), 3.07 (s, 6 H); 13C NMR (75.5 MHz, CDCl ) δ
0
3
3
3
preparation of 6-S. The crude product was purified via column
185.2, 151.7, 150.1, 136.6, 134.0, 133.2, 131.0, 129.5, 127.9, 125.6,
chromatography on SiO (1:9 Et O/CH Cl , R = 0.7) followed by
123.6, 121.1, 116.3, 114.0, 113.1, 111.7, 102.6, 40.3, 39.9; IR (film on
2
2
2
2
f
−1
recrystallization from CH Cl /hexanes to give 74 mg (62%) of 6-Se as
NaCl) 2925, 1606, 1584, 1496, 1437, 1386, 1363, 1320 cm ; HRMS
2
2
1
30
+
a yellow solid, mp >260 °C. Purity was assessed by NMR
(ESI, HRDFMagSec) m/z 447.0717 (calcd for C H N O Te + H :
21 20 2
1
spectroscopy: H NMR (500 MHz, CDCl ) δ 8.56−8.51 (m, 2 H),
447.0711).
3
7
.97 (d, 1 H, J = 9.5 Hz), 7.59 (d, 1 H, J = 9.0 Hz), 7.19 (dd, 1 H, J =
.0, 9.0 Hz), 6.89 (d, 1 H, J = 2.5 Hz), 6.85−6.80 (m, 2 H), 3.12 (s, 6
H), 3.11 (s, 6 H); C NMR (75.5 MHz, CDCl ) δ 180.9, 151.8,
Extended Rhodamine 4-S. Phenylmagnesium bromide (1.0 M in
THF, 2.87 mL, 2.87 mmol) was added to a stirred solution of 6-S (100
mg, 0.297 mmol) in THF (5 mL), and the resulting mixture was
heated at reflux for 16 h and then cooled to ambient temperature. The
reaction was quenched by the addition of glacial acetic acid (2 mL),
and the resulting mixture was poured into 100 mL of aqueous 10%
2
13
3
1
1
1
3
50.1, 136.4, 136.2, 135.9, 132.2, 126.7, 126.2, 124.8, 122.7, 120.1,
15.5, 112.0, 107.8, 106.4, 40.3, 40.0; IR (film on NaCl) 2932, 1606,
−1
582, 1507, 1407, 1372, 1329 cm ; HRMS (EI, HRDFMagSec) m/z
80
+
96.0742 (calcd for C H N O Se : 396.0742).
HPF . The resulting mixture was stirred 12 h and the precipitate was
21
20
2
6
Extended Telluroxanthone 6-Te. Diaryl Telluride 19-Te (156
collected via filtration, then washed with water (50 mL) and diethyl
mg, 0.286 mmol) and CF SO H (3 mL) were treated as described for
ether (100 mL). The crude product was recrystallized from MeOH to
3
3
1
the preparation of 6-S. The crude product was purified via
chromatography on SiO (1:9 Et O/CH Cl , R = 0.7) followed by
give 145 mg (90%) of 4-S as a dark purple solid, mp 182−183 °C: H
NMR (500 MHz, CD Cl ) δ 8.49 (d, 1 H, J = 9.5 Hz), 7.64−7.71 (m,
2
2
2
2
f
2
2
recrystallization from CH Cl /hexanes to give 65 mg (51%) of 6-Te as
3 H), 7.57 (d, 1 H, J = 9.0 Hz), 7.52 (d, 1 H, J = 9.0 Hz), 7.35−7.41
(m, 3 H), 7.32 (d, 1 H, J = 9.0 Hz), 7.28 (d, 1 H, J = 9.0 Hz), 7.11 (dd,
2
2
a yellow solid, mp >260 °C. Purity was assessed by NMR
J
DOI: 10.1021/acs.organomet.6b00255
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
1
H, J = 2.5, 9.5 Hz), 6.97 (d, 1 H, J = 2.0 Hz), 3.35 (s, 6 H), 3.25 (s, 6
C H N Se·PF : C, 53.92; H, 4.19; N, 4.66. Found: C, 54.11; H,
4.24; N, 4.64.
27
25
2
6
13
H); C NMR (75.5 MHz, CD CN) δ 161.3, 154.6, 154.0, 145.0,
3
1
1
37.5, 137.1, 136.7, 130.3, 130.0, 129.7, 129.0, 128.3, 126.9, 124.7,
Extended Rhodamine 5-Te. Phenylmagnesium bromide (1 M in
THF, 1.13 mL, 1.13 mmol) and 7-Te (50 mg, 0.113 mmol) in THF (3
mL) were treated as described for the preparation of 4-S. The crude
product was recrystallized from MeOH to give 62 mg (85%) of 5-Te
21.6, 119.7, 118.5, 117.4, 110.9, 107.3, 106.6, 41.2, 40.5; λ
max
4
−1
−1
(
MeOH) 630 nm (ε = 6.1 × 10 M cm ); λ (CH Cl ) 641
max 2 2
4
−1
−1
nm (ε = 6.5 × 10 M cm ); HRMS (ESI, HRDFMagSec) m/z
+
1
4
09.1726 (calcd for C H N S : 409.1733). Anal. Calcd for
as a dark purple solid, mp 195−196 °C. H NMR (500 MHz, CD Cl )
2
7
25
2
2
2
C H N S·PF : C, 58.48; H, 4.54; N, 5.05. Found: C, 58.54; H,
4
δ 8.19 (s, 1 H), 8.09 (s, 1 H), 7.68−7.60 (m, 3 H), 7.59−7.57 (m, 3
H), 7.34−7.36 (m, 2 H), 7.13 (d, 1 H, J = 9.5 Hz), 6.77 (d, 1 H, J = 9.0
27
25
2
6
.65; N, 5.07.
Extended Rhodamine 4-Se. Phenylmagnesium bromide (1 M in
Hz), 6.73 (s, 1 H), 3.29 (s, 6 H), 3.22 (s, 6 H); λ (MeOH) 623 nm
max
THF, 1.26 mL, 1.26 mmol) and 6-Se (50 mg, 0.126 mmol) in THF (5
mL) were treated as described for the preparation of 4-S. The crude
product was purified by recrystallization from MeOH, to give 72 mg
4
−1
−1
4
−1
(
ε = 4.89 × 10 M cm ); λ (CH Cl ) 633 nm (ε = 5.0 × 10 M
cm ); HRMS (ESI, HRDFMagSec) m/z 507.1082 (calcd for
max 2 2
−1
130
+
C H N Te : 507.1076). Anal. Calcd for C H N Te·PF : C,
2
7
25
2
27 25
2
6
1
(
95%) of 4-Se as a dark purple solid, mp 187−186 °C. H NMR (500
4
9.89; H, 3.88; N, 4.31. Found: C, 49.83; H, 3.93; N, 4.16. Material
MHz, CD Cl ) δ 8.28 (d, 1 H, J = 9.0 Hz), 7.69−7.63 (m, 3 H), 7.58
125
2
2
was too insoluble in organic solvents for the acquisition of Te and
(
7
d, 1 H, J = 10.0 Hz), 7.51 (s, 1 H), 7.45 (d, 1 H, J = 9.5 Hz), 7.37−
13
C NMR spectra.
.33 (m, 2 H), 7.31 (d, 1 H, J = 8.5 Hz), 7.28 (d, 1 H, J = 9.0 Hz), 7.00
Fluorescence Experiments. Measurements of fluorescence
quantum yields for the 4-E and 5-E dyes were performed on a
13
(
d, 1 H, J = 9.5 Hz), 6.89 (s, 1 H), 3.32 (s, 6 H), 3.24 (s, 6 H);
C
NMR (75.5 MHz, CD CN) δ 162.7, 154.1, 153.9, 147.2, 141.8, 138.7,
3
spectrofluorometer using fluorescent dye LD 700 perchlorate
1
1
=
38.6, 137.3, 130.8, 130.1, 129.8, 129.6, 128.5, 127.8, 125.7, 122.2,
38
(
Rhodamine 700) as a reference with known Φ = 0.38 in
FL
21.9, 117.5, 110.9, 109.9, 107.1, 41.3, 40.5; λ (MeOH) 647 nm (ε
max
MeOH. Each dye as well as the reference was excited at 600 nm with
4
−1
−1
4
−1
6.4 × 10 M cm ); λ (CH Cl ) 658 nm (ε = 6.9 × 10 M
max
2
2
−
1
an absorbance of 0.10 at 600 nm for the chromophore.
cm ); HRMS (ESI, HRDFMagSec) m/z 457.1178 (calcd for
C H N Se : 457.1177). Anal. Calcd for C H N Se·PF : C,
5
8
0
+
Determination of Singlet Oxygen Yields from Singlet
27
25
2
27 25
2
6
1
Oxygen Luminescence Spectroscopy. Generation of O2 was
3.92; H, 4.19; N, 4.66. Found: C, 54.16; H, 4.27; N, 4.63.
Extended Rhodamine 4-Te. Phenylmagnesium bromide (1 M in
assessed by its luminescence peak at 1270 nm. Time-resolved
1
detection of the long-lived O2 emission was used to distinguish
THF, 1.13 mL, 1.13 mmol) and 6-Te (50 mg, 0.113 mmol) in THF (3
mL) were treated as described for the preparation of 4-S. The crude
product was purified by recrystallization from MeOH to give 67 mg
36
1
signal from O as previously described. The second harmonic (532
2
nm) from a nanosecond pulsed Nd:YAG laser operating at 20 Hz was
used as the excitation source. Additional long-pass filters were used to
attenuate the scattered light and fluorescence from the samples. The
samples (methanol solutions of the compounds in quarts cuvettes)
were placed in front of the spectrometer entrance slit.
1
(
92%) of 4-Te as a dark purple solid, mp 184−185 °C. H NMR (500
MHz, CD Cl ) δ 7.93 (d, 1 H, J = 9.5 Hz), 7.78 (s, 1 H), 7.67 (d, 1 H,
2
2
J = 10.0 Hz), 7.64−7.58 (m, 3 H), 7.38−7.28 (m, 4 H), 7.24 (d, 1 H, J
=
9.5 Hz), 6.89 (d, 1 H, J = 9.5 Hz), 6.78 (s, 1 H), 3.27 (s, 6 H), 3.21
4
−1
−1
Computational Details. Calculations were done with Gaus-
(
(
s, 6 H); λmax (MeOH) 666 nm (ε = 6.5 × 10 M cm ); λ
max
4
39
−1
−1
sian09, and input files and results were visualized using Gauss-
CH Cl ) 670 nm (ε = 6.6 × 10
M
cm ); HRMS (ESI,
2
2
40
41−43
130
2
+
View05. All structures were optimized using the B3LYP
level of
HRDFMagSec) m/z 507.1073 (calcd for C H N Te : 507.1076).
Anal. Calcd for C H N Te·PF : C, 49.89; H, 3.88; N, 4.31. Found:
27
25
44−49
theory with the 6-311+G(d)
basis set for all light atoms and
27
25
2
6
50
LanL2DZ for Te. TD-DFT calculations were performed from the
optimized geometries. The UV−vis spectra were modeled with 0.17
eV fwhm Gaussians on each transition.
C, 50.08; H, 3.86; N, 4.21. Material was too insoluble in organic
solvents for the acquisition of 1 Te and C NMR spectra.
25
13
Extended Rhodamine 5-S. Phenylmagnesium bromide (1 M in
THF, 2.87 mL, 2.87 mmol) and 7-S (100 mg, 0.207 mmol) in THF (5
mL) were treated as described for preparation of 4-S. The crude
product was recrystallized from MeOH to give 145 mg (91%) of 5-S as
a dark purple solid, mp 204−205 °C. H NMR (500 MHz, CD Cl ) δ
7
ASSOCIATED CONTENT
■
1
S
*
Supporting Information
2
2
.99 (m, 2 H), 7.67−7.70 (m, 4 H), 7.49 (d, 1 H, J = 9.5 Hz), 7.41
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.6b00255.
(
dd, 2 H, J = 1.5, 8.0 Hz), 7.22 (dd, 1 H, J = 2.0, 9.0 Hz), 7.15 (d, 1 H,
J = 2.0 Hz), 6.94 (dd, 1 H, J = 2.5, 9.5 Hz), 6.89 (d, 1 H, J = 2.5 Hz),
3
1
1
4
.36 (s, 6 H), 3.25 (s, 6 H); 13C NMR (75.5 MHz, CD CN) δ 162.5,
55.7, 153.9, 147.7, 138.8, 138.5, 138.4, 136.8, 133.9, 133.3, 133.2,
30.5, 129.7, 126.4, 123.4, 121.3, 120.5, 118.6, 117.1, 107.4, 103.0,
3
Text and figures giving general methods and NMR
1
13
spectral data ( H and C NMR) for all noncommercial
4
−1
−1
1
1.6, 40.7; λmax (MeOH) 661 nm (ε = 4.71 × 10 M cm ); λ
compounds; H NMR spectra for the mixtures of
max
4
−1
−1
(CH Cl ) 689 nm (ε = 4.90 × 10
M
cm ); HRMS (ESI,
2
2
regioisomers from 11a with sec-BuLi/TMEDA and 8-E;
TD-DFT-calculated absorption spectra; and time-re-
solved singlet-oxygen emission spectra (PDF)
+
HRDFMagSec) m/z 409.1734 (calcd for C H N S : 409.1733).
Anal. Calcd for C H N S·PF : C, 58.48; H, 4.54; N, 5.05. Found: C,
5
2
7
25
2
27
25
2
6
8.23; H, 4.60; N, 4.93.
Extended Rhodamine 5-Se. Phenylmagnesium bromide (1 M in
THF, 2.53 mL, 1 M in THF, 2.53 mmol) and 7-Se (100 mg, 0.253
mmol) in THF (10 mL) were treated as described for the preparation
of 4-S. The crude product was recrystallized from MeOH to give 128
AUTHOR INFORMATION
■
*
Corresponding Authors
E-mail: t.m.mccormick@pdx.edu.
*E-mail: mdetty@buffalo.edu.
1
mg (84%) of 5-Se as a dark purple solid, mp 213-214 °C. H NMR
(
500 MHz, CD Cl ) δ 8.04 (s, 1 H), 8.00 (s, 1 H), 7.72−7.60 (m, 4
2
2
H), 7.50 (d, 1 H, J = 10.0 Hz) 7.40−7.32 (m, 3 H), 7.18 (d, 1 H, J =
Author Contributions
9
6
1
1
.0 Hz), 6.86 (d, 1 H, J = 9.5 Hz), 6.79 (s, 1 H), 3.34 (s, 6 H), 3.24 (s,
H); 13C NMR (75.5 MHz, CD CN) δ 164.0, 155.2, 154.1, 148.7,
The manuscript was written through the contributions of all
authors. All authors have given approval to the final version of
the manuscript.
3
40.6, 140.5, 138.6, 138.1, 133.6, 132.9, 130.4, 130.2, 129.6, 126.3,
24.3, 123.4, 122.2, 118.4, 116.9, 111.2, 103.1, 41.6, 40.7; λ
max
4
−1
−1
(
MeOH) 671 nm (ε = 4.71 × 10 M cm ); λ (CH Cl ) 700
max 2 2
4
−1
−1
Notes
nm (ε = 5.3 × 10 M cm ); HRMS (ESI, HRDFMagSec) m/z
4
80
+
57.1176 (calcd for C H N Se : 457.1177). Anal. Calcd for
The authors declare no competing financial interest.
27
25
2
K
DOI: 10.1021/acs.organomet.6b00255
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(
26) Jastrzebski, J. T.; Arink, A. M.; Kleijn, H.; Braam, T. W.; Lutz,
ACKNOWLEDGMENTS
■
M.; Spek, A. L.; van Koten, G. J. Am. Chem. Soc. 2013, 135, 13371−
This research was supported in part by the National Science
Foundation (Grant CHE-1151379) and by a contract from the
Wake Forest Medical Center to M.R.D. and M.W.K. The
authors also thank Tymish Y. Ohulchanskyy for his assistance
in acquiring fluorescence quantum yields and quantum yields
for the generation of singlet oxygen. T.M.M. thanks Portland
State University for financial support.
1
3378.
(27) Comins, D.; Brown, J. D. J. Org. Chem. 1984, 49, 1078−1083.
(28) Groom, K.; Hussain, S. M.; Morin, J.; Nilewski, C.; Rantanen,
T.; Snieckus, V. Org. Lett. 2014, 16, 2378−2381.
29) Del Valle, D. J.; Donnelly, D. J.; Holt, J. J.; Detty, M. R.
Organometallics 2005, 24, 3807−3810.
30) Hall, P. L.; Gilchrist, J. H.; Harrison, A. T.; Fuller, D. J.; Collum,
D. B. J. Am. Chem. Soc. 1991, 113, 9575−9585.
31) Lucht, B. L.; Collum, D. B. J. Am. Chem. Soc. 1994, 116, 7949−
7950.
(
(
(
REFERENCES
■
(32) Remenar, J. F.; Lucht, B. L.; Kruglyak, D.; Romesberg, F. E.;
(
1) Peterson, O. G.; Tuccio, S. A.; Snavely, B. B. Appl. Phys. Lett.
Gilchirst, J. H.; Collum, D. B. J. Org. Chem. 1997, 62, 5748−5754.
1
970, 17, 245−247.
(33) Williard, P. G.; Liu, Q. Y. J. Am. Chem. Soc. 1993, 115, 3380−
(
3
(
(
2) Ali, M.; Moghaddasi, J.; Ahmed, S. A. Appl. Opt. 1990, 29, 3945−
3
(
1
(
4
(
381.
34) Hall, P. L.; Gilchrist, J. H.; Collum, D. B. J. Am. Chem. Soc. 1991,
13, 9571−9574.
35) Eaton, P. E.; Carlson, G. R.; Lee, J. T. J. Org. Chem. 1973, 38,
071−4073.
36) Ohulchanskyy, T. Y.; Roy, I.; Goswami, L. N.; Chen, Y.; Bergey,
E. J.; Pandey, R. K.; Oseroff, A. R.; Prasad, P. N. Nano Lett. 2007, 7,
835−2842.
37) Adcock, W.; Wells, P. R. Aust. J. Chem. 1965, 18, 1351−1364.
38) Sauer, M.; Han, K.-T.; Muller, R.; Nord, S.; Schulz, A.; Seeger,
949.
3) Karstens, T.; Kobs, K. J. Phys. Chem. 1980, 84, 1871−1872.
4) Preininger, C.; Mohr, G. J.; Klimant, I.; Wolfbeis, O. S. Anal.
Chim. Acta 1996, 334, 113−123.
5) Liu, J.; Diwu, Z.; Leung, W.-Y.; Lu, Y.; Patch, B.; Haugland, R. P.
Tetrahedron Lett. 2003, 44, 4355−4359.
6) Shea, C. R.; Sherwood, M. E.; Flotte, T. J.; Chen, N.; Scholz, M.;
Hasan, T. Cancer Res. 1990, 50, 4167−4172.
7) (a) Lavis, L. D.; Raines, R. T. ACS Chem. Biol. 2014, 9, 855−866.
b) Grimm, J. B.; English, B. P.; Chen, J. J.; Slaughter, J. P.; Zhang, Z.
J.; Revyakin, A.; Patel, R.; Macklin, J. J.; Normanno, D.; Singer, R. H.;
Lionnet, T.; Lavis, L. D. Nat. Methods 2015, 12, 244−250.
8) Shea, C. R.; Chen, N.; Wimberly, J.; Hasan, T. Cancer Res. 1989,
9, 3961−3965.
9) Petrat, F.; Pindiur, S.; Kirsch, M.; de Groot, H. J. Biol. Chem.
003, 278, 3298−3307.
10) Pal, P.; Zeng, H.; Durocher, G.; Girard, D.; Li, T. C.; Gupta, A.
K.; Giasson, R.; Blanchard, L.; Gaboury, L.; Balassy, A.; Turmel, C.;
Laperriere, A.; Villeneuve, L. Photochem. Photobiol. 1996, 63, 161−168.
11) Ohulchanskyy, T. Y.; Donnelly, D. J.; Detty, M. R.; Prasad, P. N.
(
(
2
(
(
(
̈
(
S.; Wolfrum, J.; Arden-Jacob, J.; Deltau, G.; Marx, N. J.; Zander, C.;
Drexhage, K. J. Fluoresc. 1995, 5, 247−261.
(
39) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
(
4
(
2
Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci,
B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H.
P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.;
Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima,
T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.;
Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin,
K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.;
Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega,
N.; Millam, M. J.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.;
Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.;
Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.;
Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.;
(
(
J. Phys. Chem. B 2004, 108, 8668−8672.
12) Calitree, B. D.; Donnelly, D. J.; Holt, J. J.; Gannon, M. K.;
Nygren, C. L.; Sukumaran, D. K.; Autschbach, J.; Detty, M. R.
Organometallics 2007, 26, 6248−6257.
13) Kryman, M. W.; Schamerhorn, G. A.; Hill, J. E.; Calitree, B. D.;
(
̈
(
Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, O.;
Davies, K. S.; Linder, M. K.; Ohulchanskyy, T. Y.; Detty, M. R.
Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09,
Revision D.01; Gaussian, Inc.: Wallingford, CT, 2009.
(40) Dennington, R.; Keith, T.; Millam, J. GaussView, version 5;
Semichem Inc.: Shawnee Mission, KS, 2009.
Organometallics 2014, 33, 2628−2640.
(
14) Hill, J. E.; Linder, M. K.; Davies, K. S.; Sawada, G. A.; Morgan,
J.; Ohulchanskyy, T. Y.; Detty, M. R. J. Med. Chem. 2014, 57, 8622−
634.
15) Kryman, M. W.; Davies, K. S.; Linder, M. K.; Ohulchanskyy, T.
Y.; Detty, M. R. Bioorg. Med. Chem. 2015, 23, 4501−4507.
16) Mann, J. R.; Gannon, M. K.; Fitzgibbons, T. C.; Detty, M. R.;
Watson, D. F. J. Phys. Chem. C 2008, 112, 13057−13061.
17) Mulhern, K. R.; Detty, M. R.; Watson, D. F. J. Phys. Chem. C
011, 115, 6010−6018.
18) Mulhern, K. R.; Detty, M. R.; Watson, D. F. J. Photochem.
Photobiol., A 2013, 264, 18−25.
19) McCormick, T. M.; Calitree, B. D.; Orchard, A.; Kraut, N. D.;
Bright, F. V.; Detty, M. R.; Eisenberg, R. J. Am. Chem. Soc. 2010, 132,
5480−15483.
20) Yang, Y.; Lowry, M.; Escobedo, J. O.; Sibrian-Vazquez, M.;
(
41) Becke, A. D. Phys. Rev. A: At., Mol., Opt. Phys. 1988, 38, 3098−
100.
42) Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B: Condens. Matter
Mater. Phys. 1988, 37, 785−789.
43) Miehlich, B.; Savin, A.; Stoll, H.; Preuss, H. Chem. Phys. Lett.
989, 157, 200−206.
44) Hehre, W. J.; Ditchfield, R.; Pople, J. A. J. Chem. Phys. 1972, 56,
257−2261.
45) Hariharan, P. C.; Pople, J. A. Theor. Chem. Acc. 1973, 28, 213−
22.
46) Francl, M. M.; Pietro, W. J.; Hehre, W. J.; Binkley, J. S.;
DeFrees, D. J.; Pople, J. A.; Gordon, M. S. J. Chem. Phys. 1982, 77,
654−3665.
47) Binning, R. C., Jr.; Curtiss, L. A. J. Comput. Chem. 1990, 11,
206−1216.
48) Rassolov, V. A.; Pople, J. A.; Ratner, M. A.; Windus, T. L. J.
Chem. Phys. 1998, 109, 1223−1229.
49) Rassolov, V. A.; Ratner, M. A.; Pople, J. A.; Redfern, P. C.;
Curtiss, L. A. J. Comput. Chem. 2001, 22, 976−984.
50) Bauernschmitt, R.; Ahlrichs, R. Chem. Phys. Lett. 1996, 256,
54−464.
8
(
3
(
(
(
1
(
2
(
2
(
(
2
(
(
1
(
3
(
1
(
Wong, L.; Showalter, C. M.; Jensen, T. J.; Fronczek, F. R.; Warner, I.
M.; Strongin, R. M. Proc. Natl. Acad. Sci. U. S. A. 2008, 105, 8829−
8834.
(
21) Sibrian-Vazquez, M.; Escobedo, J. O.; Lowry, M.; Fronczek, F.
R.; Strongin, R. M. J. Am. Chem. Soc. 2012, 134, 10502−10508.
22) Brennan, N. K.; Donnelly, D. J.; Detty, M. R. J. Org. Chem.
(
(
(
4
2
(
(
(
003, 68, 3344−3347.
23) Chen, C. W.; Beak, P. J. Org. Chem. 1986, 51, 3325−3334.
24) Gay, R.; Hauser, C. R. J. Am. Chem. Soc. 1967, 89, 2297−2303.
25) Coll, G.; Morey, J.; Costa, A.; Saa, J. M. J. Org. Chem. 1988, 53,
5345−5348.
L
DOI: 10.1021/acs.organomet.6b00255
Organometallics XXXX, XXX, XXX−XXX