Synthesis, structure, and optical properties of terminally sulfur-functionalized core-substituted naphthalene-bisimide dyes

Article abstract of DOI:10.1002/hlca.200690190

The synthesis, characterization, and optical properties of a series of new 2,6-disubstituted naphthalene-bisimide dyes as molecular rods comprising terminal AcS groups is reported. The first series of dyes (1-3), comprising phenylhetero (Ph-X) core substituents, cover a broad range of the VIS spectrum, ranging from yellow (2) over red (3) to blue (1). The second series of dyes contains benzylhetero (Bn-X) core substituents (4-7). For the same heteroatom connecting the substituent to the naphthalene core, both series were found to display comparable colors. For the second series, the colors were blue (4), red (5), and violet (6, 7). The Ph-X-substituted dyes 1-3 are nonfluorescent, in contrast to the Bn-X-substituted compounds 4-7. This rich variety of optical features that can be adjusted by rather small alterations of the core substituents makes these structurally very comparable molecular rods ideal candidates for optically triggered molecular-transport investigations. Also, thanks to the terminal AcS groups, these compounds can be placed between nobel-metal electrodes for optically triggered transport experiments.

Full text of DOI:10.1002/hlca.200690190

1986
Helvetica Chimica Acta – Vol. 89 (2006)
Synthesis, Structure, and Optical Properties of Terminally Sulfur-
Functionalized Core-Substituted Naphthalene-Bisimide Dyes
by Alfred Błaszczyka)b), Matthias Fischera), Carsten von Hänischa), and Marcel Mayor*a)c)
a) Institute for Nanotechnology, Forschungszentrum Karlsruhe GmbH, P. O. Box 3640,
D-76021 Karlsruhe
b
´
´
) Faculty of Commodity Science, Al. Niepodległosci 10, 60-967 Poznan, Poland
c) University of Basel, Department of Chemistry, St. Johannsring 19, CH-4056 Basel
(e-mail: marcel.mayor@unibas.ch)
The synthesis, characterization, and optical properties of a series of new 2,6-disubstituted naphtha-
lene-bisimide dyes as molecular rods comprising terminal AcS groups is reported. The first series of dyes
(1–3), comprising phenylhetero (Ph-X) core substituents, cover a broad range of the VIS spectrum, rang-
ing from yellow (2) over red (3) to blue (1). The second series of dyes contains benzylhetero (Bn-X) core
substituents (4–7). For the same heteroatom connecting the substituent to the naphthalene core, both
series were found to display comparable colors. For the second series, the colors were blue (4), red
(5), and violet (6, 7). The Ph-X-substituted dyes 1–3 are nonfluorescent, in contrast to the Bn-X-substi-
tuted compounds 4–7. This rich variety of optical features that can be adjusted by rather small alterations
of the core substituents makes these structurally very comparable molecular rods ideal candidates for
optically triggered molecular-transport investigations. Also, thanks to the terminal AcS groups, these
compounds can be placed between nobel-metal electrodes for optically triggered transport experiments.
Introduction. – In the last few years, several terminally sulfur (S)-functionalized
molecules have been successfully immobilized on a single-molecule level between
two electrodes, and correlations between their molecular structures and electronic-
transport properties have been revealed to some extent [1][2]. A current challenge is
to extend such molecular-electronic-transport arrangements with an additional signal
capable of triggering the current through the molecular structure. First examples of a
single-molecule device responding to an electrochemical trigger have already been
reported [3–5]. Alternatively, light may also serve as an external trigger of the elec-
tronic current. While molecular switches [6] and shuttles [7] between different electro-
des have already been reported, our current focus is to combine electronic excitation of
the immobilized molecule with electronic transport. In particular, we strive towards the
investigation of optically triggered currents through single molecules, and of single-
molecule electroluminescence. Against this background, our interest in rod-like and
terminally S-functionalized dye molecules becomes reasonable.
Herein, we report the synthesis, structural analysis, and optical properties of a series
of core-substituted naphthalene-bisimide dyes, i.e., the rod-like compounds 1–7, com-
prising terminal acetyl (Ac)-protected S-atoms.
2. Results and Discussion. – 2.1. General Strategy. An ideal dye structure for the
envisaged experiments has to fulfill several requirements. For single-molecule experi-
ꢀ 2006 Verlag Helvetica Chimica Acta AG, Zürich

Helvetica Chimica Acta – Vol. 89 (2006)
1987
ments in mechanically controlled break junctions (MCB) and junctions based on elec-
tromigration, rigid rod-like structures with terminal Ac-protected S-atoms proved to be
ideally suited [8][9]. The distance between both terminal S-atoms should be ca. 2 nm.
Furthermore, the optical properties of the molecular structure should be adjustable to
the equipment of the experiment station. In particular, dye structures providing differ-
ent absorption and emission properties as a function of lateral substituents, without
changing the rigid rod-type backbone, are of great interest. Finally, processability, sol-
ubility, and, of course, ready chemical access are crucial requirements.
During the search for an ideally suited basic dye structure, we became aware of the
studies of Würthner and co-workers on core-substituted naphthalene bisimides as flu-
orophores [10] and as H-bond-directed surface-structure motives [11]. Already the
size and the structural symmetry of the naphthalene-bisimide dye were very appealing.
In particular, the moleculesꢁ symmetry should be reflected in transport investigations,
as has been shown for oligo(phenylene-ethynyl) rods [8]. Furthermore, its color is
reported to be tunable by the core substituent [10]. Moreover, the fluorescence of
the dye seems to depend to some extent on the core substituents. In particular, naph-
thalene-bisimide dyes with phenylamine substituents are reported to be nonfluorescent
[10]. This is a particular interesting feature for optoelectronic, molecule-based devices,
as it allows tracking the origin of an observed effect by comparison experiments of two
very similar molecules that differ strongly in only one particular optical property. Alto-
gether, the naphthalene-bisimide subunit appeared ideally suited for the envisaged
experiments. However, the compounds had to be terminally substituted by AcS groups
to become immobilizable between two metallic electrodes.
2.2. Synthesis. The retro-synthetic approach to the desired core unit A is shown in
Scheme 1. To provide processability, in particular solubility and chemical stability of
the intermediates, the terminal S-atoms were introduced as (tert-butyl)sulfanyl groups.
The condensation of 4-[(tert-butyl)sulfanyl]benzen-1-amine and 2,6-dichloronaphtha-

1988
Helvetica Chimica Acta – Vol. 89 (2006)
Scheme 1. Synthetic Strategy to Access Terminally Acetylsulfanyl-Functionalized Naphthalene-Bis-
imide Dyes
lene bisanhydride should provide the chlorinated naphthalene bisimide derivative 8.
Nucleophilic substitution of the Cl-atoms by O-, N-, S-, or Se nucleophiles should
then provide access to a variety of dye structures B of varying colors. To keep the
shape of the series of dyes comparable and to integrate the option to quench the fluo-
rescence, only heteroatom-linked phenyl (Ph) and benzyl (Bn) groups were considered
as core substituents. To guarantee solubility of the target dye structures, these Ph and
Bn groups had to carry additional peripheral tBu groups. Finally, exchange of the tB u by
Ac groups at both terminal S-atoms would provide a series of core-substituted naphtha-
lene-bisimide dyes A.
All here reported dyes were prepared from the common precursor 8, i.e., N,N’-
bis{[4-(tert-butyl)sulfanyl]phenyl}-2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic acid
bisimide1), the synthesis of which is displayed in Scheme 2. Both starting compounds
for the synthesis of 8 are known [12][13]. While 2,6-dichloronaphthalene-1,4,5,8-tetra-
carboxylic acid bisanhydride (9) was synthesized according to a literature procedure
[13], the synthesis of 4-[(tert-butyl)sulfanyl]aniline (10) [12] has been slightly modified.
First, the F-atom of commercially available 1-fluoro-4-nitrobenzene (11) was substi-
tuted by a tBuS group by treatment with 1.2 equiv. of sodium 2-methylpropane-2-thio-
late in anhydrous DMF for 1 h. The mixture was not heated since this nucleophilic aro-
matic substitution is exothermic and initially heats the reaction mixture considerably.
After workup and column chromatography, compound 12 was isolated in 91% yield
as a light-yellow solid. Subsequently, the NO2 group of 12 was reduced with Sn in
HCl/EtOH to afford 10 as a yellowish solid in 95% yield. Next, the bisanhydride 9
was treated with 3.5 equiv. of the aniline 10 in AcOH at 1108. Neither the starting bisan-
1
)
For systematic names, see Exper. Part.

Helvetica Chimica Acta – Vol. 89 (2006)
1989
hydride 9 nor the resulting target compound 8 were soluble under these reaction con-
ditions. However, immediately after the addition of the aniline 10, the suspended bisan-
hydride 9 completely dissolved, and product 8 started to precipitate as a brown solid,
which was isolated by filtration in 67% yield. During the synthesis of 8, a side product
was formed, which gave rise to a signal at m/z 808.74 in the MALDI-TOF mass spec-
trum. This compound, which was formed in considerable amounts, was formed by sub-
stitution of one of the Cl-atoms of the naphthalene core of 8 with 10 as the nucleophile,
which points at the reactivity of the Cl-atoms towards nucleophilic substitution. Finally,
to overcome the poor solubility of 8, its Cl-atoms were substituted by Ph-X and Bn-X
groups (X=NH, O, S, Se) comprising additional peripheral tBu groups to prevent the
molecules from forming hardly soluble stacks. This gave rise to compounds 13–20 (see
Scheme 2 and Scheme 4 below).
Our first attempts were focused on dye structures comprising peripheral Ph-X sub-
t
stituents. Thus, Bu-substituted anilines, phenols, and thiophenols were considered as
nucleophiles for the core functionalization of the naphthalene bisimide. While 3,5-
di(tert-butyl)aniline and 4-(tert-butyl)thiophenol are commercially available, 3,5-
di(tert-butyl)phenol was synthesized in 96% yield by hydrolysis of commercially avail-
able 3,5-di(tert-butyl)phenyl trifluoromethanesulfonate according to a literature proce-
dure [14].
As displayed in Scheme 2, the Ph-substituted dyes comprising terminal tBuS groups
were synthesized by the method of Vollmann et al. [13]. The dichloro precursor 8 was
treated with an excess of the corresponding nucleophile in DMF as a nonprotic polar
solvent. The synthesis of the dark-blue [3,5-di(tert-butyl)phenyl]amino-substituted
dye 13 was accomplished in 70% yield with 6 equiv. of the aniline at 1208 for 16 h.
The role of 3,5-di(tert-butyl)aniline in this nucleophilic substitution is twofold: on
one hand, it serves as the nucleophile proper, on the other hand, it acts as a base to
catch the liberated HCl during the reaction.
The 3,5-di(tert-butyl)phenoxy- and the [4-(tert-butyl)phenyl]sulfanyl-substituted
dyes 14 and 15, respectively, could be prepared at lower temperature (608) in the pres-
ence of 3 equiv. of the corresponding nucleophiles as well as K2CO3 as base. To keep the
reaction temperature as low as possible (ca. 608) turned out to be crucial for an efficient
synthesis of the desired dyes, as decomposition of both the starting material 8 and the
products was observed at elevated temperatures under these conditions. After chroma-
tographic purification, the intense-yellow and red dyes 14 and 15 were isolated in 63
and 76% yield, respectively.
According to the strategy described above, the three Ph-substituted dyes 13–15
t
with terminal BuS groups were transformed to the target dye structures 1–3 with
AcS groups. Following a reported procedure [15], compounds 13–15 were treated
with BBr3 in CH2Cl2/toluene/AcCl. Compound 1 was isolated in 21% yield as a dark-
blue solid. Acetylation of the [3,5-di(tert-butyl)phenyl]amino substituents was observed
as a side reaction, which rationalized, to some extent, the rather low yield. Compound
1a, a dark-violet side product containing an additional Ac group at one of the periph-
eral amino substituents, was isolated in 18% yield after column chromatography, and
was fully characterized. Furthermore, the formation of 4-methylacetophenone was
observed under the reaction conditions. As this compound is also formed in absence
of the dye molecules, it is most likely formed by a Friedel–Crafts acylation of the co-sol-

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Helvetica Chimica Acta – Vol. 89 (2006)

Helvetica Chimica Acta – Vol. 89 (2006)
1991
vent toluene by AcCl, with BBr3 acting as Lewis acid. Finally, the dyes 2 and 3, which
cannot be further acetylated, were isolated in yields of 84% and 72% as yellow and red
solids, respectively.
For the syntheses of dyes 4–7, the precursors required to introduce the peripheral
substituents, [4-(tert-butyl)phenyl]methanamine, [4-(tert-butyl)phenyl]methanol, and
[4-(tert-butyl)phenyl]methanethiol, were commercially available. To expand the series,
[4-(tert-butyl)phenyl]methaneselenol (21) was synthesized according to Scheme 3.
Commercially available 1-(bromomethyl)-4-(tert-butyl)benzene was treated with 2
equiv. of potassium selenocyanate in anhydrous MeCN at room temperature to afford
the selenocyanate 22 as a colorless solid in 96% yield [16][17]. Reduction of 22 with 2
equiv. of Li[Et
3A
ꢀ788, resulted in the Ac-protected selenol 23 as a colorless oil [18]. The Ac group of 23
was then cleaved according to a reported procedure [19] by treatment with excess AcCl
in anhydrous, degassed MeOH at ꢀ788 to afford 21 as a crude, colorless oil, which was
used without characterization and purification in the following synthetic steps.
Scheme 3
a) KSeCN, MeCN, r.t., 16 h; 96%. b) 1. Li[Et
3A
c) AcCl, MeOH, ꢀ788 ! r.t.
As displayed in Scheme 4, comparable reaction conditions as described above for
the Ph-X-substituted dyes enabled the assembly of Bn-X-functionalized analogues
t
comprising Bu-protected terminal S-atoms.
Treatment of the dichloro precursor 8 in anhydrous 1,3-dimethylimidazolidinone
(DMI) with an excess of [4-(tert-butyl)phenyl]methanamine at 908 gave the desired pre-
cursor 16 as a blue solid in 42% yield after chromatographic purification and recrystal-
lization from i-PrOH. The monosubstituted intermediate was identified by MALDI-
TOF-MS (M+ at m/z 790.6488) as a major side product. The choice of DMI as solvent
for this reaction turned out to be crucial. In our first attempts, we used DMF instead of
DMI, and substitution of the Cl-atoms of 8 by Me2ACHTRENUGN H, most likely arising from decom-
posing DMF, was observed.
After numerous standard procedures had failed with respect to the synthesis of 17, a
suspension of 8 in CH2Cl2 was treated with a large excess of the freshly prepared Na
alcoholate of [4-(tert-butyl)phenyl]methanol. After 3 h at ambient temperature, aque-
ous extraction and purification, the desired naphthalene-bisimide derivative 17 was
obtained as a yellow-brownish solid in poor yield (18%).

1992
Helvetica Chimica Acta – Vol. 89 (2006)
Scheme 4
a) 4-tBuC6H4CH2NH2; DMI, 908, 4 h; 42%. b) 4-tBuC Oꢀ Na+, CH2Cl2, r.t., 3 h; 18%. c) 4-
6ACHTREUNGH4ACHRETCUNG H2ACHTREUNG
tBuC6H4CH2SH, DMF, K2CO3, 508, 45 min; 79%. d) 4-tBuC6H4CH2SeH, DMF, K2CO3, r.t., 45 min;
24%. e) 4-tBuC6H4CH2NH2, DMI, 408, 8 h; 61%. f) B B3,rAcCl, CH2Cl2, toluene, r.t., ca. 1 h. g) 4-
tBuC6H4CH2SH, K2CO3, DMF, 508, 1 h; 73%.
For the synthesis of the benzylsulfanyl-substituted precursor 18, even milder reac-
tion conditions had to be applied than for the phenylsulfanyl precursor 15 due to the
higher reactivity of alkylthiolates compared to arylthiolates. The dichloro precursor 8
was, thus, treated with [4-(tert-butyl)phenyl]methanethiol in anhydrous, degassed
DMF with K2CO3 as base at 508 for 45 min. Compound 18 was isolated in 79% yield
as a strongly fluorescent red-violet solid after chromatographic purification. Thereby,
the product yield decreased considerably with increasing reaction temperature.
Organoselenocyanates like 22 have been reported as precursors of selenolates upon
reaction with reducing agents like NaBH4 [20] or on alkaline hydrolysis with hydroxides
[21] or K2CO3 [22]. However, naphthalene bisimides are also susceptible to reducing
agents [23][24] and strong hydroxides [25]. In our first attempt, compound 22 and 8
in anhydrous, degassed DMF were treated with K2CO3 to generate the benzylic seleno-
late in situ. However, only traces of the desired dye precursor 19 were obtained after
workup. In the next attempt, the starting materials were dissolved in THF, and
NaBH4 was tested for the formation of the benzylic selenolate. However, under
these conditions, the desired product was isolated in only 5% yield. Competing reac-
tions, either reaction between the formed selenolate and organoselenocyanate [26] to

Helvetica Chimica Acta – Vol. 89 (2006)
1993
form the diselenide, or nucleophilic substitution of the Cl-atoms of 8 by cyano nucleo-
philes, may account for this. To improve the yield of 19, the free selenol 21 was prepared
(see Scheme 3) and used for the nucleophilic substitution. When a mixture of 8 and
K2CO3 in DMF was treated with an excess of 21, the desired dye precursor 19 was iso-
lated in 24% yield after purification as a dark-red solid. Whether the rather poor yield
is due to the high reactivity of the selenolates or because of the powerful reducing prop-
erties of selenols was not further investigated [27][28].
A similar protocol as described above for the Ph-X-substituted compounds was
next applied for the replacement of the tBu group by Ac protecting groups. Thus, pre-
cursor 16 was treated with BBr3 in CH2Cl2, and then exposed to AcCl in toluene for 1 h
to afford the desired target dye 4 as a blue solid in 53% yield after chromatographic
purification. Similar as described above for 1, acetylation of the amino substituent of
4 was observed as a side reaction (M+ at m/z 971.51). However, this additionally ace-
tylated side product was not isolated and further characterized.
Applying similar reaction conditions for the group exchange of the BnO-substituted
dye precursor 17 did not provide the desired compound. When a solution of 17 in
CH2Cl2, AcCl, and toluene was treated with BBr3 in CH2Cl2 at room temperature, a
dark-red solid precipitated. During aqueous workup and extraction with CH2Cl2, the
organic phase turned yellow, and after column chromatography, the 2,6-dihydroxy com-
t
pound 17a, still comprising the BuS groups, was isolated as the main product in 36%
yield (Scheme 4). As BBr3 is known to cleave benzyl ethers [29], debenzylation and
the resulting considerable decrease in solubility were not surprising. Next, we tried
to remove the tBu groups with catalytic amounts of Br2 in AcCl and toluene [30]. How-
ever, a large number of compounds of varying polarities were formed, but not the
desired reaction product. However, for the benzylsulfanyl and -seleno precursors 18
and 19, respectively, the BBr3 replacement protocol applied for the formation of 4 pro-
vided the desired Ac-protected dye structures. The target dye 5 was isolated in 65%
yield as a red solid, and the benzylseleno-substituted dye 6 was obtained in 59%
yield as a violet solid.
Finally, we were interested in the noncentrosymmetric dye 7 with mixed substitu-
ents (Scheme 4). First, one of the Cl-atoms of 8 was substituted with the benzylamine.
Thus, 8 was treated with 2 equiv. of [4-(tert-butyl)phenyl]methanamine in DMI at 408.
The role of the second equivalent of amine was to capture the protons evolved during
the reaction. The desired monosubstituted dye precursor 20 was isolated as a red solid
in 61% yield. Its remaining Cl-atom was then replaced by exposure to [4-(tert-butyl)-
phenyl]methanethiol in the presence of K2CO3 in DMF at 508, which afforded the non-
symmetric precursor 20a in 73% yield as a violet solid. The choice of the order of intro-
duction of the two side groups turned out to be crucial, as the increased reactivity of the
benzylsulfanylate as a nucleophile results almost exclusively in the doubly substituted
t
precursor 18, even upon treatment with excess 8. Subsequent replacement of the Bu
moieties of 20a by AcS groups was finally achieved by the same protocol as applied
for the synthesis of 1–6 (BBr3 in CH2Cl2/AcCl/toluene), which afforded 7 as a violet
solid after purification in 61% yield. Again, additional acetylation of the benzylamino
substituent was observed as side reaction, as detected by MALDI-TOF-MS (M+ at m/z
974.75).

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Helvetica Chimica Acta – Vol. 89 (2006)
2.3. Structure Elucidation. Compounds 1–7 were found to be reasonably soluble in
nonprotic solvents like toluene or THF, and well-soluble in chlorinated organic solvents
such as CH2Cl2 or CHCl3. Their structures, including those of the precursors, were con-
firmed by 1H- and 13C-NMR spectroscopy, MALDI-TOF-MS, elemental analysis, and,
in the case of 1, also by single-crystal X-ray-diffraction analysis (Fig. 1). Crystals were
obtained by slow diffusion of EtOH into a CH2Cl2 solution of 1. Interestingly, only sam-
ples containing considerable amounts of 4-methylacetophenone gave single crystals
suitable for X-ray analysis. Compound 1 was found to crystallize with two independent,
inversion-symmetric molecules and one molecule of 4-methylacetophenone in the tri-
t
2
ꢀ
clinic space group P1 ). Some of the Bu groups are disordered and have been refined
with split positions concerning the Me units. The intramolecular S···S distance in 1 is
1.88(3) nm. The benzene rings of the 4-(AcS)-C6H4 groups are nearly perpendicular to
the central naphthalene bisimide core, the torsion angles C(5)ꢀC(6)ꢀN(1)ꢀC(9) and
C(5)ꢀC(6)ꢀN(1)ꢀC(13) amounting to 109.24(7)8 and 72.03(8)8, respectively.
2.4. Optical Properties. 2.4.1. Dyes 1–3. The UV/VIS absorption spectra of dyes 1–3
in CH2Cl2 at room temperature are shown in Fig. 2. As expected from their different
colors, the variation of the heteroatom connecting the naphthalene bisimide core and
the Ph substituents results in considerably different absorption spectra. Their UV/
VIS spectra are divided in three groups of absorption bands. While the short-wave-
length peaks between 250 and 315 nm and the color-determining longest-wavelength
absorptions between 400 and 700 nm depend considerably on the substituents in posi-
tions 2 and 6 of the naphthalene-bisimide core, the central absorption bands, with max-
ima below 380 nm, are barely affected by the peripheral substituents. The observation
that these bands are independent of the core substituents and remain outside the VIS
range has already been reported as the origin of the high brilliancy of 2,6-disubstituted
naphthalene bisimides [10].
The short-wavelength absorption maxima at 315 nm (1) or 256 nm (2) were found
to be shifted bathochromically with increasing strength of the electron-donating char-
acter of the core substituents. The same tendency, with even stronger shifts, was
observed for the longest-wavelength absorptions, which consist of a broad maximum
with a shoulder towards shorter wavelength. The maxima are at 462 nm for the phen-
oxy-substituted dye 2, and at 626 nm for 1 with its two phenylamino substituents. The
strong effect of the electron-donor substituents on the absorption properties was attrib-
2
)
Crystallographic data: formula: C58H58N4O6S2 ·C9H10O, lattice parameters: a=1042.7(2),
b=1579.0(3), c=1987.5(4) pm, a=112.05(3), b=95.66(3), g=92.28(3)8, V=3007.6(11)·106 pm3; tri-
clinic, space group P1, Z=2; 1calc =1.193 g cmꢀ1; m(MoKa)=0.144 mmꢀ1, STOE IPDS2, MoKa-radi-
ꢀ
ation, l=0.71073 Š; T=180 K; 2qmax =458; 10053 reflections measured, 6751 independent reflec-
tions (Rint =0.0608), 5070 independent reflections with Fo >4s(Fo). The structure was solved by direct
methods and refined by full-matrix least-squares techniques against F2, 810 parameters. S, O, N, and
t
C were refined anisotropically, H-atoms were calculated at ideal positions. Three Bu groups were
refined with split positions, no H-atoms were fitted to these groups. R1=0.0807; wR2=0.2254 (all
data); Gof: 1.016; maximum peak 0.247 e Šꢀ3. CCDC-606900 contains the supplementary crystallo-
graphic data for this paper. These data can be obtained, free of charge, at www.ccdc.cam.ac.uk/conts/
retrieving.html or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge
CB21EZ, UK (fax: +44-1223-336033; e-mail: deposit@ccdc.cam.ac.uk).

Helvetica Chimica Acta – Vol. 89 (2006)
1995
Fig. 1. X-Ray single-crystal structure of 1 (ORTEP representation, thermal ellipsoids set at the 40%-
t
probability level). H-atoms have been omitted for clarity; only one orientation of the disordered Bu
groups is shown. Selected bond lengths (in pm) and bond angles (in 8): C(1)ꢀC(2) 149.6(6), C(2)ꢀ
O(1) 119.7(5), C(2)ꢀS(1) 178.4(5), S(1)ꢀC(3) 176.6(4), C(3)ꢀC(4) 138.1(6), C(4)ꢀC(5) 138.8(5),
C(5)ꢀC(6) 133.8(6), C(6)ꢀC(7) 140.6(5), C(7)ꢀC(8) 139.6(5), C(8)ꢀC(3) 135.9(6), C(6)ꢀN(1)
146.7(4), N(1)ꢀC(9) 138.1(5), C(9)ꢀO(2) 121.2(5), C(9)ꢀC(10) 148.3(5), C(10)ꢀC(11) 140.4(5),
C(11)ꢀC(12) 142.0(5), C(12)ꢀC(13) 145.9(5), C(13)ꢀO(3) 122.5(5), C(13)ꢀN(1) 140.2(5), C(12)ꢀ
C(14) 140.8(5), C(14)ꢀN(2) 137.0(5), C(10)ꢀC(15) 137.0(6), C(15)ꢀC(14’) 142.0(5), C(11)ꢀC(11’)
141.4(7); C(2)ꢀS(1)ꢀC(3) 102.7(2), C(9)ꢀN(1)ꢀC(13) 126.4(3).
uted to the electronic S0 ! S1 transition, which has been assumed to arise from inter-
actions between the electron-donor substituents and the C=O functional groups [10].
The short- and the long-wavelength maxima of 3 at 295 nm and 519 nm, respec-
tively, are both clearly shifted bathochromically compared to 2, pointing at an increased
electron-donating character of the phenylsulfanyl substituent compared with the phen-
oxy substituents in 2.
2,6-Arylamino-substituted naphthalene-bisimide dyes have been reported to be
nonfluorescent, and intramolecular bonding of the amino H-atom to the adjacent
C=O group is considered as the major pathway for radiationless deactivation of the
excited state [10], in analogy to numerous commercial UV absorbers [31]. Therefore,
the lack of a detectable fluorescence signal for 1 was not surprising. However, also
the phenoxy- and phenylsulfanyl-substituted dyes 2 and 3, without the possibility of
H-bonding, were found to be nonfluorescent. We assume that the high-lying HOMO

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Helvetica Chimica Acta – Vol. 89 (2006)
Fig. 2. UV/VIS Spectra of 1–3 (ca. 10 mM) in CH2Cl2 at room temperature
of the electron-donor substituents is quenching the excited state by electron transfer
into the singly occupied former HOMO of the chromophore as an alternative pathway
for radiationless deactivation. Details of the intramolecular-quenching mechanism are
currently under investigation with suitable model compounds.
Considering the electron-donor Ph-X substituents as the origin of the radiationless
deactivation of the excited state, our interest moved towards naphthalene-bisimide
dyes comprising benzyl substituents. By altering the structure from Ph-X to Bn-X sub-
stituents, shape, size and solubility of the dye molecule should remain to a large extend
comparable, but the peripheral p-substituents are separated electronically, and the
hypothesized quenching mechanism may be suppressed.
2.4.2. Dyes 4–7. The electronic-absorption spectra of the benzyl-substituted dyes
4–6 are shown in Fig. 3. At a first glance, they are very similar to those of the corre-
sponding phenyl derivatives (see Fig. 2). Again, there are three absorption regions,
one at short wavelength (280–310 nm), a second set of bands with maxima below
380 nm, and, finally, a color-determining longest-wavelength region that strongly
depends on the core substituents. Again, the longest-wavelength absorptions were
found to be broad, their shoulder to shorter wavelength being slightly more pro-
nounced. The longest-wavelength absorption of 4 (610 nm) is shifted hypsochromically
compared to the analogue 1 (626 nm). The longest-wavelength absorptions of both 5
(528 nm) and 3 (519 nm) are comparable. In case of the seleno congener 6, the maxi-
mum lies at 553 nm, in between the maxima of the S- and N-analogues 5 and 4, respec-
tively, as expected from its violet color. While the short-wavelength absorption of dyes
1–3 follows in their order that of their longest-wavelength absorption, this order is no
longer maintained for the series 4–6, with maxima at 283, 297, and 308 nm, respec-
tively.

Helvetica Chimica Acta – Vol. 89 (2006)
1997
Fig. 3. UV/VIS Spectra of 4–7 (ca. 10 mM) in CH2Cl2 at room temperature
Of particular interest were the photoluminescence properties of these new series of
dyes (Fig. 4). Strong fluorescence properties had already been observed during the
reaction and upon chromatographic purification of 4 and 5 (excitation at 254 nm
upon TLC analysis), but not for the benzylseleno compound 6. Qualitative investiga-
tion by fluorescence spectroscopy displayed, indeed, an intense fluorescence signal
for 4 upon excitation at 610 nm (Fig. 4). Even with a very diluted sample of 4 (0.177
mM) and minimal excitation energy, a strong fluorescence signal with a maximum at
642 nm was recorded. This intense fluorescence signal further challenges the proposed
radiationless deactivation of the excited state by H-bonding with the C=O group, as the
benzylamine core substituents of 4 also provide H-atoms required for the suggested
mechanism. Similar observations have been reported before for alkylamine-substituted
naphthalene bisimides [10].
The benzylthio-substituted dye 5 displayed a fluorescence maximum at 558 nm
upon excitation at 528 nm. However, the intensity of the signal was weaker than that
observed for 4: both the sample concentration (13.1 mM) and the excitation energy
had to be increased. By further increasing the excitation energy, a fluorescence signal
at 594 nm was even observed for a solution of the benzylseleno-substituted dye 6 (11.1
mM) upon excitation at 553 nm. The considerably reduced intensity of the fluorescence
signal of 6 compared to those of the analogues 4 and 5 can be rationalized by an internal
heavy-atom effect of the Se substituents, as reported for example for chalcogeno-xan-
thylium dyes [32]. The Stoke shifts of 4–6 were 32–42 nm, which is slightly larger than
those reported for comparable chromophores comprising alkyl-X substituents in 2- and
6-position [10].
The rather weak fluorescence properties of the Se-substituted dye 6, with its lon-
gest-wavelength absorption maximum between those of the S- and N-substituted ana-

1998
Helvetica Chimica Acta – Vol. 89 (2006)
Fig. 4. UV/VIS Absorption and fluorescence spectra of 4–7 in CH2Cl2 at room temperature. The fluo-
rescence signals are normalized to the intensities of the absorption maxima. Concentrations of the
samples (and excitation wavelengths) in fluorescence experiments: 4: 0.177 mM (610 nm); 5: 13.1 mM
(528 nm); 6: 11.1 mM (553 nm); 7: 0.186 mM (567 nm).
logues, inspired the design of compound 7, comprising both a [(tert-butyl)phenyl]amino
and a [(tert-butyl)phenyl]sulfanyl substituent. The substitution pattern of 7 should pro-
vide absorption and emission bands at comparable wavelengths as in the case of 6, but
the lack of Se should increase the fluorescence intensity.
The UV/VIS spectrum of 7 was found to be comparable to those of the other mem-
bers of the Bn series (see Fig. 3 above). As intended, the longest-wavelength absorption
of 7 at 567 nm lies in between those of 4 and 5. Furthermore, the position of the absorp-
tion maximum is comparable to that of the Se dye 6 (552 nm). The nonsymmetric dye 7
showed a very strong fluorescence signal at 596 nm upon excitation at 567 nm (Fig. 4).
As anticipated, 7 displays with 596 nm a fluorescence signal at comparable wavelength
as the Se compound 6 (594 nm), but with considerably increased intensity, almost com-
parable to that observed for 1.
Conclusions. – A series of rod-type dyes, 1–7, with terminal AcS groups comprising
a 2,6-disubstituted naphthalene-bisimide chromophore, were synthesized and analyzed.
Due to peripheral tBu groups at the Ph or Bn substituents, respectively, the dyes display
reasonable solubility in organic solvents. The choice of the hetero-atoms at C(2) and
C(6) of the naphthalene-bisimide core allow one to adjust the longest-wavelength
absorption and, thus, the compound color over a wide range of the visible spectrum.
Furthermore, the chemical nature of the core substituents enables one to tailor the fluo-
rescence properties of these compounds. While rods with phenyl-heteroatom substitu-
ents are nonfluorescent, those with benzyl-heteroatoms are fluorescent. The molecular-
rod motive containing two anchor groups for metal electrodes at both ends with this

Helvetica Chimica Acta – Vol. 89 (2006)
1999
broad range of addressable optical properties has been designed for optically triggered
transport investigations in metal–molecule hybrid setups. While experiments along this
idea are currently performed, the structural motive is further extented to enable single-
molecule-electroluminescence experiments and optically triggered directional trans-
port in molecule–metal hybrid structures.
We are grateful for financial support by the Swiss National Science Foundation and the German Min-
istry of Education and Research. We are thankful to Valerie Chaurin for her support in fluorescence inves-
tigations. We also thank Thomas Carell for fruitful discussions.
Experimental Part
General. All chemicals were used as received; solvents were of anal. quality, used without further
purification, and dried by standard procedures; in particular, THF was distilled from Na/benzophenone,
and CH2Cl2 was distilled over CaH [33]. Anh. 1,3-dimethylimidazolidinone (DMI) was purchased from
Fluka, and anh. DMF and MeCN were from Aldrich. TLC: Merck silica gel 60 F254 plates. Column chro-
matography (CC): Merck silica gel 60 (0.040–0.063 mm). Melting points (m.p.) were measured on a
Büchi B-540 apparatus; uncorrected. UV/VIS Spectra: Varian Carry-500Scan spectrophotometer, with
1-cm quartz cuvettes, at r.t.; lmax in nm (e in l molꢀ1cmꢀ1). Fluorescence spectra: Shimadzu RF-5301
PC spectrofluorometer, with 1-cm quartz cuvettes, at r.t. 1H- and 13C-NMR Spectra: Bruker Ultra-
Shield-300 apparatus, at 300 and 75 MHz, resp.; d in ppm, J in Hz; all spectra were recorded at 258, unless
noted otherwise. MALDI-TOF-MS: PerSeptive Biosystems Voyager-DE-PRO time-of-flight mass spec-
trometer; EI-MS: Finnigan MAT-95Q mass spectrometer; in m/z (rel. %). Elemental analyses: Thermo-
Quest FlashEA 1112-N protein analyzer.
1-(1,1-Dimethylethyl)sulfanyl-4-nitrobenzene (12). Prepared as reported in [34]. Briefly, a mixture of
4-fluoro-1-nitrobenzene (11.1 g, 0.079 mol) and sodium 2-methyl-2-propanethiolate (14.3081 g, 0.1276
mol) in anh. DMF (200 ml) was stirred for 1 h at r.t. The mixture was poured into brine and extracted
with Et2ACHTEROUNG . After evaporation of the solvents of the org. phase, the crude product was purified by filtration
through a short column of SiO2 eluting with hexane/CH2Cl2 2 :1. Yield: 15.1938 g (91%). Yellowish solid.
M.p. 39–408 (lit. m.p. 39.5–40.58 [12]). 1H-NMR (CDCl3): 1.29 (s, 3 Me); 7.63 (d, 3J=8.7, 2 H); 8.12 (d,
3J=8.7, 2 H). 13C-NMR (CDCl3): 31.14 (Me); 47.58 (MeC); 123.37, 136.90, 142.39, 147.76. EI-MS: 211.1
(13, M+), 155.0 (12, [MꢀC4H8]+), 57.1 (100, C
Hþ9 ).
4ACHTREUNG
4-[(1,1-Dimethylethyl)sulfanyl]benzene-1-amine (10). To a soln. of 12 (7.4451 g, 0.035 mol) in EtOH
(150 ml), conc. HCl (4 ml) and Sn powder (8.3083 g, 0.07 mol) were added in one portion, which gave rise
to an exothermic reaction. The mixture was stirred for 1 h without cooling. After neutralization with
NaOH, extraction with toluene, and evaporation of the solvents, the crude product was purified by
CC (SiO2; hexane/CH2Cl2 2 :1). Yield: 6.0492 g (95%). Yellowish solid. M.p. 69–708 (lit. m.p. 71–728
[12]). 1H-NMR (CDCl3): 1.23 (s, 3 Me); 3.80 (s, NH2); 6.59 (d, 3J=8.4, 2 H); 7.28 (d, 3J=8.4, 2 H).
13C-NMR (CDCl3): 30.72; 45.32; 114.93; 120.49; 138.77; 147.16. EI-MS: 181.1 (17, M+), 125.0 (100,
[MꢀC4H8]+).
4,9-Dichloro-2,7-bis{4-[(1,1-dimethylethyl)sulfanyl]phenyl}benzo[lmn][3,8]phenanthroline-1,3,6,8-
(2H,7H)-tetrone (8). 2,6-Dichloronaphthalene-1,4,5,8-tetracarboxylic acid bisanhydride (9) (4.0695 g,
0.0121 mol) was suspended in glacial AcOH (300 ml) and heated at 1108. Then, 3.5 equiv. of 10 was
added, and the mixture was kept at 1108 for another 30 min. After the addition of 10, a soln. was
obtained, out of which a brownish solid started to precipitate. The precipitate was filtered off and washed
repeatedly with hot AcOH to afford 8 (5.3528 g) in 67% yield. Brown solid. M.p.>4108. UV/VIS
1
(CH2Cl2): 401 (13300), 380 (12200), 358 (20700), 340 (15000), 250 (57800). H-NMR (C
D2Cl4, 1008):
3
3
1.47 (s, 6 Me); 7.34 (d, J=7.8, 4 H); 7.79 (d, J=8.1, 4 H); 8.88 (s, 2 H). MALDI-TOF-MS: 663.6268
(M+, C Sþ calc. 662.0862). Anal. calc. for C34H28Cl2N2O4S2 (663.63): C 61.54, H 4.25, N
H
G
CHTREUNGN CHTEURNGO CHTREUNG
2
;
4.22; found: C 60.25, H 4.31, N 4.20. Due to the very poor solubility of the material, we were not able
to record its 13C-NMR spectrum.

2000
Helvetica Chimica Acta – Vol. 89 (2006)
3,5-Bis(1,1,dimethylethyl)phenol. Prepared according to [14]. To a soln. of 3,5-bis(1,1-dimethyl-
ethyl)phenyl trifluoromethanesulfonate (4.236 g, 0.0125 mol) in 1,4-dioxane (50 ml), Bu4A
N+OHꢀ (20%
CTHREUNG
soln. in H2O; 32.94 ml, 0.025 mol) was added, and the mixture was stirred for 1 h at r.t. Approximately
half of the 1,4-dioxane was removed under reduced pressure, and the mixture was poured into H2O and
extracted with CH2Cl2. The combined org. layers were dried and concentrated, and the residue was puri-
fied by CC (SiO2; hexane/CH2Cl2 1:1). Yield: 2.4714 g (96%). Colorless solid. M.p. 89–918 (lit. m.p.
89.5–908 [35]). 1H-NMR (CDCl3): 1.31 (s, 6 Me); 4.40 (br. s, OH); 6.70 (d, 4J=1.5, 2 H); 7.01 (t,
4J=1.5, 1 H). 13C-NMR (CDCl3): 31.53; 34.99; 109.79; 115.08; 152.75; 155.01. EI-MS: 206.2 (24, M+),
191.2 (100, [MꢀCH3]+), 57.1 (51, C
Hþ9 ).
4ACHTREUNG
4,9-Bis{[3,5-bis(1,1-dimethylethyl)phenyl]amino}-2,7-bis{4-[(1,1-dimethylethyl)sulfanyl]phenyl}ben-
zo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone (13). A mixture of 8 (0.5575 g, 0.84 mmol) and 3,5-
bis(1,1-dimethylethyl)benzen-1-amine (1.035 g, 5.04 mmol) in anh. DMF (10 ml) was kept at 1208 for
16 h. After evaporation of the solvent, the residue was purified by CC (SiO2; hexane/CH2Cl2 1:2).
1
Yield: 0.5851 g (70%). Blue solid. M.p. 370–3728. H-NMR (CDCl3): 1.34 (s, 12 Me); 1.39 (s, 6 Me);
7.17 (s, 4 H); 7.32 (s, 2 H); 7.34 (d, 3J=8.4, 4 H); 7.74 (d, 3J=8.1, 4 H); 8.66 (s, 2 H). 13C-NMR
(CDCl3): 31.20; 31.53; 35.09; 46.44; 102.93; 118.68; 120.28; 121.18; 122.72; 126.38; 128.87; 133.99;
135.74; 137.54; 138.32; 148.01; 152.76; 162.72; 166.54. MALDI-TOF-MS: 1000.7866 (M+, C S2þ ;
62CAHTREUNGH72ACHTERUNNG 4ACHTRENUOG 4ACHTREUNG
calc. 1000.4990). Anal. calc. for C62H72N4O4S2 (1001.39): C 74.36, H 7.25, N 5.59; found: C 74.42, H 7.23, N
5.63.
4,9-Bis{[3,5-bis(1,1-dimethylethyl)phenyl]oxy}-2,7-bis{4-[(1,1-dimethylethyl)sulfanyl]phenyl}benzo-
[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone (14). A mixture of 8 (1.0192 g, 1.5 mmol), 3,5-bis(1,1-
dimethylethyl)phenol (0.9506 g, 4.61 mmol), and K2CO3 (0.6371 g, 4.61 mmol) in anh. DMF (10 ml)
was kept at 608 for 2 h. The mixture was poured into H2O and extracted with CH2Cl2. The combined
org. phases were concentrated under reduced pressure, and the residue was purified by CC (SiO2; hex-
ane/CH2Cl2 1:2). Yield: 0.9482 g (63%). Yellow solid. M.p. 345–3478. 1H-NMR (CDCl3): 1.30 (s, 12 Me);
3
1.31 (s, 6 Me); 6.99 (d, 4J=1.5, 4 H); 7.25–7.33 (m, 6 H); 7.68 (d, J=8.4, 4 H); 8.37 (s, 2 H). 13C-NMR
(CDCl3): 31.01; 31.36; 35.15; 46.31; 112.21; 114.99; 120.06; 123.26; 124.66; 127.60; 128.84; 133.74; 135.28;
138.21; 153.62; 153.78; 160.36; 160.83; 161.99. MALDI-TOF-MS: 1003.8168 (M+, C S2þ ; calc.
62CAHTREUNGH70ACHTERUNNG 2ACHTRENUOG 6ACHTREUNG
1002.4670). Anal. calc. for C62H70N2O6S2 (1003.36): C 74.22, H 7.03, N 2.79; found: C 74.25, H 6.95, N 2.89.
4,9-Bis{[4-(1,1-dimethylethyl)phenyl]sulfanyl}-2,7-bis{4-[(1,1-dimethylethyl)sulfanyl]phenyl}benzo-
[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone (15). A mixture of 8 (0.1520 g, 0.229 mmol), 4-(1,1-
dimethylethyl)benzenethiol (0.1143 g, 0.687 mmol), and K2ACTHERNGUCO3 HCATRE(UGN 0.095 g, 0.687 mmol) in anh., degassed
DMF (10 ml) was kept at 608 for 1 h. The mixture was poured into H2O and extracted with CH2Cl2.
The combined org. phases were collected and concentrated under reduced pressure, and the resulting res-
idue was separated by CC (SiO2; hexane/CH2Cl2 1:2). Yield: 0.1618 g (76%). Red solid. M.p.>4108. 1H-
NMR (CDCl3): 1.35 (s, 12 Me); 7.27 (d, 3J=8.4, 4 H); 7.53 (d, 3J=8.7, 4 H); 7.57 (d, 3J=8.7, 4 H); 7.70 (d,
3J=8.1, 4 H); 8.31 (s, 2 H). 13C-NMR (CDCl3): 31.18; 31.32; 35.10; 46.52; 118.48; 124.28; 125.88; 126.09;
127.76; 128.81; 130.48; 134.31; 135.13; 135.76; 138.40; 150.97; 154.40; 162.29; 163.50. MALDI-TOF-MS:
923.1648 (M+, C S4þ ; calc. 922.2961). Anal. calc. for C54H54N2O4S4 (923.27): C 70.25, H 5.89, N
54CAHTREUNGH54ACHTERUNNG 2ACHTRENUOG 4ACHTREUNG
3.03; found: C 70.43, H 5.89, N 3.16.
S,S’-[(4,9-Bis{[3,5-bis(1,1-dimethylethyl)phenyl]amino}-1,3,6,8-tetrahydro-1,3,6,8-tetraoxobenzo[lmn]-
[3,8]phenanthroline-2,7-diyl)dibenzene-4,1-diyl] Diethanethioate (1) and S,S’-[(4-{Acetyl[3,5-bis(1,1-
dimethylethyl)phenyl]amino}-9-{[3,5-bis(1,1-dimethylethyl)phenyl]amino}-1,3,6,8-tetrahydro-1,3,6,8-tet-
raoxobenzo[lmn][3,8]phenanthroline-2,7-diyl)dibenzene-4,1-diyl] Diethanethioate (1a). To a soln. of 13
(0.4327 g, 0.432 mmol) in CH2Cl2 (100 ml), toluene (40 ml), and AcCl (40 ml), a soln. of BBr3 in
CH2Cl2 (4 ml) was added at 08. The mixture was stirred for 1 h at r.t. Then, the violet soln. was poured
into ice-water, and the org. residue was extracted with CH2Cl2 and purified by CC (SiO2; CH2Cl2) to
afford 1 (0.088 g, 21%) and 1a (0.08 g, 18%).
Data of 1. Blue solid. M.p. 358–3618. UV/VIS (CH2Cl2): 626 (22700), 371 (15800), 352 (15800), 315
1
4
(41900), 237 (43700). H-NMR (CDCl3): 1.32 (s, 12 Me); 2.46 (s, 2 Me); 7.15 (d, J=1.8, 4 H); 7.28 (t,
4J=1.8, 2 H); 7.39 (d, 3J=8.4, 4 H); 7.63 (d, 3J=8.4, 4 H); 8.73 (s, 2 H); 11.06 (s, 2 NH). 13C-NMR
(CDCl3): 30.45; 31.53; 35.12; 102.98; 118.22; 120.14; 121.23; 122.81; 126.39; 129.33; 129.61; 135.12;

Helvetica Chimica Acta – Vol. 89 (2006)
2001
Sþ2 ;
136.14; 137.57; 147.76; 152.77; 162.66; 166.51; 192.88. MALDI-TOF-MS: 972.2391 (M+, C
H
U
O
N
calc. 972.3949). Anal. calc. for C58H60N4O6S2 (973.25): C 71.58, H 6.21, N 5.76; found: C 71.43, H 6.09, N
5.81.
1
Data of 1a. Violet solid. M.p. 315–3168. H-NMR (CDCl3): 1.31 (s, 6 Me); 1.34 (s, 6 Me); 2.07 (s,
AcN); 2.46 (s, 2 AcS); 7.16 (s, 2 H); 7.32 (s, 2 H); 7.34–7.45 (m, 7 H); 7.57–7.69 (m, 4 H); 8.46 (s, 1
H); 8.73 (s, 1 H); 11.63 (s, NH). 13C-NMR (CDCl3): 23.52; 30.44; 31.47; 35.10; 35.13; 100.75; 118.58;
121.14; 122.35; 122.66; 123.10; 124.67; 128.75; 128.84; 129.17; 129.44; 129.51; 129.67; 133.18; 135.05;
135.22; 135.93; 136.08; 136.62; 140.20; 141.92; 150.62; 153.02; 153.06; 162.20; 162.30; 162.48; 166.34;
172.25 (NC=O); 192.77; 192.89; one signal masked. FAB-MS: 1015.4 (M+, C S2þ ; calc. 1014.4).
60CAHTREUNGH62ACHTERUNNG 4ACHTRENUOG 7ACHTREUNG
S,S’-[(4,9-Bis{[3,5-bis(1,1-dimethylethyl)phenyl]oxy}-1,3,6,8-tetrahydro-1,3,6,8-tetraoxobenzo[lmn]-
[3,8]phenanthroline-2,7-diyl)dibenzene-4,1-diyl] Diethanethioate (2). To a soln. of 14 (0.7598 g, 0.757
mmol) in CH2ACHTREUCGN l2 CAHTRE(UGN 70 ml), toluene (14 ml), and AcCl (50 ml), a soln. of BBr3 in CH2ACHTUEGCRN l2 AHCTRE(UGN 7 ml) was
added dropwise at r.t. The mixture was stirred for 30 min at r.t., poured into ice-water, and extracted
with CH2Cl2. The combined org. phases were collected and concentrated at reduced pressure. The result-
ing residue was separated by CC (SiO2; CH2Cl2). Yield: 0.6217 g (84%). Yellow solid. M.p. 355–3578.
1
UV/VIS (CH2Cl2): 462 (17300), 437 (12700), 362 (15500), 350 (15700), 256 (54100). H-NMR (CDCl3):
1.30 (s, 12 Me); 2.43 (s, 2 Me); 6.99 (d, 4J=1.8, 4 H); 7.32 (s, 2 H); 7.38 (d, 3J=8.4, 4 H); 7.57 (d,
3J=8.1, 4 H); 8.38 (s, 2 H). 13C-NMR (CDCl3): 30.39; 31.43; 35.22; 112.62; 114.75; 120.08; 123.62;
124.92; 127.74; 129.23; 129.64; 135.06; 135.72; 153.83; 153.85; 160.30; 160.89; 162.07; 193.01. MALDI-
TOF-MS: 975.3077 (M+, C S2þ ; calc. 974.3629). Anal. calc. for C58H58N2O8S2 (975.22): C
58CAHTREUNGH58ACHTERUNNG 2ACHTRENUOG 8ACHTREUNG
71.43, H 5.99, N 2.87; found: C 71.52, H 5.96, N 2.99.
S,S’-[(4,9-Bis{[4-(1,1-dimethylethyl)phenyl]sulfanyl}-1,3,6,8-tetrahydro-1,3,6,8-tetraoxobenzo[lmn]-
[3,8]phenanthroline-2,7-diyl)dibenzene-4,1-diyl] Diethanethioate (3). To a soln. of 15 (0.1444 g, 0.156
mmol) in CH2ACHTREGCUN l2 ACHRTEU(GN 15 ml), toluene (3 ml), and AcCl (10 ml), a soln. of BBr3 in CH2Cl2 (1.5 ml) was
added at r.t. The mixture was stirred for 30 min at r.t., poured into ice-water, and extracted with
CH2Cl2. The combined org. phases were collected, and concentrated at reduced pressure. The resulting
residue was separated by CC (SiO2; CH2Cl2). Yield: 0.1006 g (72%). Red solid. M.p. 367–3698. UV/VIS
(CH2Cl2): 519 (23800), 486 (13400), 373 (15900), 356 (14500), 295 (51000), 258 (33300). 1H-NMR
3
3
(CDCl3): 1.35 (s, 6 Me); 2.45 (s, 2 Me); 7.35 (d, J=8.4, 4 H); 7.50–7.56 (m, 8 H); 7.59 (d, J=8.4, 4
H); 8.25 (s, 2 H). 13C-NMR (CDCl3): 30.42; 31.37; 35.15; 118.53; 124.28; 125.85; 126.30; 127.76;
129.63; 129.65; 130.50; 135.15; 135.62; 135.83; 151.14; 154.53; 162.13; 163.38; 192.78. Anal. calc. for
C50H42N2O6S4 (895.14): C 67.09, H 4.73, N 3.13; found: C 66.90, H 4.83, N 3.34. MALDI-TOF-MS:
895.3359 (M+, C Sþ4 ; calc. 894.1920).
50CAHTREUNGH42ACHTERUNNG 2ACHTRENUOG 6ACHTREUNG
[4-(1,1-Dimethylethyl)phenyl]methyl Selenocyanate (22). To a soln. of 1-(bromomethyl)-4-(1,1-dime-
thylethyl)benzene (7.416 g, 0.0326 mol) in anh. MeCN (10 ml), potassium selenocyanate (9.4079 g, 0.0653
mol) was added in one portion at 08. The mixture was stirred for 16 h at r.t., poured into ice-water, and
extracted with Et2ACHTREUONG . The combined org. phases were collected, and the solvents were removed at reduced
pressure. The resulting colorless residue was recrystallized from hexane to afford 7.8692 g (96%) of the
title compound. Colorless crystals. M.p. 93–948. 1H-NMR (CDCl3): 1.33 (s, 3 Me); 4.31 (s, CH2); 7.31 (d,
3J=8.1, 2 H); 7.40 (d, 3J=8.4, 2 H). 13C-NMR (CDCl3): 31.33; 32.83; 34.78; 102.27; 126.20; 128.85; 132.32;
151.97. EI-MS: 253.1 (0.1, M+), 147.1 (100, [MꢀSeCN]+), 132.1 (38.9), 117.1 (21.2), 91.0 (7.7). Anal. calc.
for C12H15NSe (252.22): C 57.15, H 5.99, N 5.55; found: C 57.04, H 6.13, N 5.60.
Se-{[4-(1,1-Dimethylethyl)phenyl]methyl} Ethaneselenoate (23). To a soln. of 22 (2.3875 g, 9.5 mmol)
in anh., degassed THF, maintained at ꢀ788 under N2 atmosphere, was added dropwise a 1M soln. of
Super-Hydrideꢂ in THF (19 ml, 19 mmol). After 15 min, the reaction was quenched with 10 equiv. of
degassed Ac2O (9 ml, 95 mmol) at ꢀ788. The mixture was allowed to warm to r.t. over 1 h, poured
into ice-water, and extracted with Et2ACHTREOUNG . The combined org. phases were collected and concentrated at
reduced pressure. The resulting residue was separated by CC (SiO2; hexane/CH2Cl2). Yield: 2.1368 g
1
3
(83.5%). Colorless oil. H-NMR (CDCl3): 1.36 (s, 3 Me); 2.46 (s, 3 Me); 4.20 (s, CH2); 7.27 (d, J=8.4,
2 H); 7.36 (d, 3J=8.4, 2 H). 13C-NMR (CDCl3): 28.98; 31.39; 34.50; 34.51; 125.58; 128.59; 136.04;
149.87; 197.48. EI-MS: 270.1 (4.2, M+), 147.1 (100, [MꢀC2H3OSe]+), 132.1 (19.5), 117.1 (11.0).
[4-(1,1-Dimethylethyl)phenyl]methaneselenol (21). To a soln. of 23 (0.6570 g, 2.44 mmol) in anh.,
degassed MeOH (15 ml) was slowly added at ꢀ788 an excess of AcCl (1 ml) under N2 atmosphere.

2002
Helvetica Chimica Acta – Vol. 89 (2006)
The mixture was kept at this temp. for 30 min, and then allowed to warm to r.t. over a period of 2 h under
N2 atmosphere. Removal of the volatile products at reduced pressure provided the crude title compound
as a colorless oil, which was dissolved in anh., degassed DMF, and directly used in the following steps
without purification.
4,9-Bis({[4-(1,1-dimethylethyl)phenyl]methyl}amino)-2,7-bis{4-[(1,1-dimethylethyl)sulfanyl]phenyl}-
benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone (16). A soln. of 8 (0.5237 g, 0.789 mmol) and 4-
(1,1-dimethylethyl)benzen-1-amine (0.5153 g, 3.16 mmol) in DMI (5 ml) was kept at 908 for 4 h. After
evaporation of the solvents, the crude mixture was purified by CC (SiO2; CH2Cl2) and recrystallization
1
from i-PrOH. Yield: 0.3029 g (42%). Blue solid. M.p.>4108. H-NMR (CDCl3): 1.30 (s, 6 Me); 1.38 (s,
3
3
3
3
6 Me); 4.62 (d, J=5.7, 4 H); 7.29 (d, J=8.4, 8 H); 7.35 (d, J=8.4, 4 H); 7.72 (d, J=8.4, 4 H); 8.30
(s, 2 H); 9.61 (t, 3J=5.7, 2 NH). 13C-NMR (CDCl3): 31.21; 31.43; 34.68; 46.52; 47.13; 102.49; 119.34;
122.03; 126.07; 126.46; 127.43; 128.84; 134.13; 134.l9; 135.81; 138.44; 149.55; 151.00; 163.12; 166.41.
MALDI-TOF-MS: 915.8814 (M+,
Sþ2 ; calc. 916.4051). Anal. calc. for C56H60N4O4S2
C56ACHTREUNHG 60ACHRTEUNNG 4ACHTRENUOG 4ACHTREUNG
(917.23): C 73.33, H 6.59, N 6.11; found: C 73.44, H 6.40, N 6.19.
4,9-Bis({[4-(1,1-dimethylethyl)phenyl]methyl}oxy)-2,7-bis{4-[(1,1-dimethylethyl)sulfanyl]phenyl}-
benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone (17). To a suspension of 8 (0.3250 g, 0.49 mmol)
in anh. CH2Cl2 (25 ml), sodium [4-(1,1-dimethylethyl)phenyl]methanolate (1 ml) – prepared by dissolv-
ing Na (1.08 g, 4.71 mmol) in [4-(1,1-dimethylethyl)phenyl]methanol (5 ml, 3.14 mmol) – was added. The
mixture was stirred for 3 h at r.t., poured into H2O, and extracted with CH2Cl2. After removal of the sol-
vents, the residue was purified by CC (SiO2; CH2Cl2). Yield: 0.0788 g (17.5%). Yellow-brownish solid.
1
3
M.p. ca. 3308 (dec.). H-NMR (CDCl3): 1.28 (s, 6 Me); 1.37 (s, 6 Me); 5.49 (s, 2 CH2); 7.30 (d, J=8.4,
4 H); 7.38 (d, 3J=8.4, 4 H); 7.49 (d, 3J=8.4, 4 H); 7.71 (d, 3J=8.4, 4 H); 8.59 (s, 2 H). 13C-NMR
(CDCl3): 31.24; 31.42; 34.77; 46.50; 71.96; 111.76; 120.61; 124.36; 126.00; 127.38; 127.62; 128.99;
132.04; 134.04; 135.62; 138.35; 151.72; 160.29; 160.95; 162.60. MALDI-TOF-MS: 916.7705 (M+,
58A
Sþ2 ; calc. 918.3731).
C56ACTHERUNHG CHTRUENNG 2ACHTRENUOG 6ACHTREUNG
2,7-Bis{4-[(1,1-dimethylethyl)sulfanyl]phenyl}-4,9-dihydroxybenzo[lmn][3,8]phenanthroline-1,3,6,8-
(2H,7H)-tetrone (17a). To a solution of 17 (0.035 g, 0.038 mmol) in CH2Cl2 (10 ml), toluene (10 ml), and
AcCl (5 ml), a soln. of BBr3 in CH2Cl2 (0.2 ml) was added dropwise at r.t. A red solid started to precip-
itate. The mixture was stirred for 30 min at r.t., poured into ice-water, and extracted with CH2Cl2, which
resulted in a color change from red to yellow. The combined org. phases were concentrated at reduced
pressure, and the residue was purified by CC (SiO2; CH2Cl2). Yield: 0.0086 g (36%). Yellow solid.
1
3
3
M.p.>4108. H-NMR (CDCl3): 1.38 (s, 6 Me); 7.31 (d, J=8.1, 4 H); 7.76 (d, J=8.1, 4 H); 8.39 (s, 2
H); 12.14 (s, 2 OH). MALDI-TOF-MS: 627.4142 (M+, C S2þ ; calc. 626.1540). Due to the very
34CAHTREUNGH30ACHTERUNNG 2ACHTRENUOG 6ACHTREUNG
poor solubility of the material, we were not able to record its 13C-NMR spectrum.
4,9-Bis({[4-(1,1-dimethylethyl)phenyl]methyl}sulfanyl)-2,7-bis{4-[(1,1-dimethylethyl)sulfanyl]phe-
nyl}benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone (18). A soln. of 8 (0.6456 g, 0.973 mmol), [4-
(1,1-dimethylethyl)phenyl]methanethiol (0.7018 g, 3.89 mmol), and K2CO3 (0.4034 g, 2.92 mmol) in
anh., degassed DMF (10 ml) was kept at 508 for 45 min. The solvent was evaporated, and the crude mix-
ture was purified by CC (SiO2; hexane/CH2Cl2 1:1 ! 1:6). Yield: 0.7336 g (79%). Red-violet solid. M.p.
308–3098. 1H-NMR (CDCl3,): 1.29 (s, 6 Me); 1.37 (s, 6 Me); 4.33 (s, 2 CH2); 7.28–7.34 (m, 10 H); 7.37 (d,
3
3J=8.4, 4 H); 7.70 (d, J=8.7, 4 H); 8.76 (s, 2 H). 13C-NMR (CDCl3): 31.18; 31.38; 34.67; 37.18; 46.47;
118.72; 123.87; 125.12; 125.94; 128.62; 128.91; 129.27; 131.09; 134.20; 134.94; 138.31; 149.54; 151.09;
162.18; 163.16. MALDI-TOF-MS: 948.5477 (M+, C S4þ ; calc. 950.3274). Anal. calc. for
56CAHTREUNGH58ACHTERUNNG 2ACHTRENUOG 4ACHTREUNG
C56H58N2O4S4 (951.32): C 70.70, H 6.14, N 2.94; found: C 70.64, H 6.21, N 3.11.
4,9-Bis({[4-(1,1-dimethylethyl)phenyl]methyl}selanyl)-2,7-bis{4-[(1,1-dimethylethyl)sulfanyl]phe-
nyl}benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone (19). To a soln. of 21 (0.5544 g, 2.44 mmol) in
anh., degassed DMF (10 ml), K2CO3 (0.3372 g, 2.44 mmol) and 8 (0.2348 g, 0.354 mmol) were added. The
color of the mixture turned to green. The mixture was stirred for 45 min at r.t., poured into H2O, and
extracted with CH2Cl2. The solvent was evaporated at reduced pressure, and the residue was purified
1
by CC (SiO2; CH2Cl2). Yield: 0.0891 g (24%). Dark-red solid. M.p. 272–2748. H-NMR (CDCl3): 1.28
3
3
3
(s, 6 Me); 1.37 (s, 6 Me); 4.29 (s, 2 CH2); 7.30 (d, J=8.4, 6 H); 7.34 (d, J=8.4, 6 H); 7.71 (d, J=8.4,
4 H); 8.83 (s, 2 H). 13C-NMR (CDCl3): 31.07 (SeCH2); 31.30; 31.42; 34.69; 46.48; 121.31; 123.53;

Helvetica Chimica Acta – Vol. 89 (2006)
2003
125.96; 126.33; 128.91; 129.27; 131.21; 132.19; 134.53; 135.03; 138.19; 147.53; 150.76; 162.42; 163.95. Anal.
calc. for C56H58N2O4S2Se2 (1045.12): C 64.36, H 5.59, N 2.68; found: C 64.12, H 5.63, N 2.89. MALDI-
TOF-MS: 1044.4933 (M+, C Seþ2 ; calc. 1044.2187).
56CATHRUENGH58ACHTRUENNG 2ACHERTUNGO4ACHRTEGNUS2ACHTRENUG
4-Chloro-9-({[4-(1,1-dimethylethyl)phenyl]methyl}amino)-2,7-bis{4-[(1,1-dimethylethyl)sulfanyl]-
phenyl}benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone (20). A soln. of 8 (0.6406 g, 0.965 mmol)
and 4-(1,1-dimethylethyl)benzene-1-amine (0.3152 g, 1.93 mmol) in DMI (10 ml) was kept at 408 for
8 h. The mixture was poured in H2O, and the precipitate was collected by filtration. The filtrate was con-
centrated at reduced pressure, and purified by CC (SiO2, CH2Cl2). Yield: 0.4633 g (61%). Red solid. M.p.
230–2338. 1H-NMR (CDCl3): 1.29 (s, 3 Me); 1.37 (s, 3 Me); 1.38 (s, 3 Me); 4.70 (d, 3J=5.7, 2 H);
3
3
3
7.24–7.33 (m, 6 H); 7.37 (d, J=7.8, 2 H); 7.71 (d, J=7.5, 2 H); 7.73 (d, J=7.5, 2 H); 8.41 (s, 1 H);
8.64 (s, 1 H); 10.27 (t, J=5.6, NH). 13C-NMR (CDCl3): 31.16; 31.21; 31.38; 34.69; 46.54; 47.25; 100.60;
3
121.52; 121.89; 122.43; 124.36; 126.24; 127.40; 127.91; 128.69; 128.75; 128.85; 133.08; 133.97; 134.28;
134.30; 135.14; 135.24; 135.43; 138.39; 138.41; 151.40; 152.04; 161.30; 161.95; 162.09; 166.10. MALDI-
TOF-MS: 790.6488 (M+, C S2þ ; calc. 789.2456). Anal. calc. for C45H44ClN3O4S2 (790.43): C
45CATHERUNGH44ACTHERCUNG lN3ACHTURENOG 4ACHTREGUN
68.38, H 5.61, N 5.32; found: C 68.79, H 5.67, N 5.40.
4-({[4-(1,1-Dimethylethyl)phenyl]methyl}amino)-9-({[4-(1,1-dimethylethyl)phenyl]methyl}sulfanyl)-
2,7-bis{4-[(1,1-dimethylethyl)sulfanyl]phenyl}benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone
(20a). To a solution of 20 (0.406 g, 0.514 mmol) in anh., degassed DMF (10 ml), [4-(1,1-dimethylethyl)-
phenyl]methanethiol (0.1852 g, 1.03 mmol), and K2CO3 (0.1423 g, 1.03 mmol) were added. The mixture
was kept at 508 for 1 h, and then poured into H2O, and extracted with CH2Cl2. The combined org. phases
were concentrated at reduced pressure, and the residue was purified by CC (SiO2; hexane/CH2Cl2 7:3 !
0 :1). Yield: 0.3515 g (73%). Blue-violet solid. M.p. 299–3028. 1H-NMR (CDCl3): 1.28 (s, 3 Me); 1.29 (s, 3
Me); 1.34 (s, 3 Me); 1.37 (s, 3 Me); 4.30 (s, SCH2); 4.64 (d, 3J=5.1, NCH2); 7.26–7.39 (m, 12 H); 7.68 (d,
3J=8.7, 2 H); 7.74 (d, 3J=8.4, 2 H); 8.32 (s, 1 H); 8.75 (s, 1 H); 10.01 (t, 3J=5.4, NH). 13C-NMR (CDCl3):
31.12; 31.17; 31.35; 31.38; 34.63; 34.65; 36.98; 46.46; 46.48; 47.24; 100.45; 119.31; 120.12; 121.20; 123.09;
125.79; 126.12; 126.32; 126.93; 127.64; 128.14; 128.82; 128.87; 129.28; 131.41; 133.17; 133.94; 134.08;
135.04; 135.45; 138.34; 138.45; 144.49; 150.81; 150.93; 151.24; 162.21; 162.73; 163.37; 165.97. MALDI-
TOF-MS: 932.6744 (M+, C S3þ ; calc. 933.3662). Anal. calc. for C56H59N3O4S3 (934.28): C
56CAHTREUNGH59ACHTERUNNG 3ACHTRENUOG 4ACHTREUNG
71.99, H 6.37, N 4.50; found: C 72.23, H 6.41, N 4.45.
S,S’-{[4,9-Bis({[4-(1,1-dimethylethyl)phenyl]methyl}amino)-1,3,6,8-tetrahydro-1,3,6,8-tetraoxobenzo-
[lmn][3,8]phenanthroline-2,7-diyl]dibenzene-4,1-diyl} Diethanethioate (4). To a soln. of 16 (0.4168 g,
0.454 mmol) in CH2Cl2 (100 ml), toluene (40 ml), and AcCl (40 ml), a soln. of BBr3 in CH2Cl2 (4 ml)
was added dropwise at 08. The mixture was stirred for 1 h at r.t, poured into ice-water, and extracted
with CH2Cl2. The combined org. phases were concentrated at reduced pressure, and the residue was puri-
fied by CC (SiO2; CH2Cl2/AcOEt). Yield: 0.2122 g (53%). Blue solid. M.p. 281–2838. UV/VIS (CH2Cl2):
610 (22000), 563 (11100), 364 (14000), 347 (12100), 283 (47500). Fluorescence spectrum (CH2Cl2): lmax
1
3
3
642 nm. H-NMR (CDCl3, 458): 1.28 (s, 6 Me); 2.47 (s, 2 Me); 4.58 (d, J=5.1, 4 H); 7.26 (d, J=8.4, 4
3
3
3
3
H); 7.32 (d, J=8.4, 4 H); 7.40 (d, J=8.4, 4 H); 7.58 (d, J=8.4, 4 H); 8.12 (s, 2 H); 9.46 (t, J=5.1, 2
NH). 13C-NMR (CDCl3, 458): 30.39; 31.44; 34.68; 47.32; 102.16; 119.01; 121.75; 126.07; 126.27; 127.75;
129.29; 129.78; 133.89; 135.10; 136.23; 149.30; 151.09; 162.81; 166.16; 192.80. MALDI-TOF-MS:
887.7246 (M+, C S2þ ; calc. 888.3010). Anal. calc. for C52H48N4O6S2 (889.09): C 70.25, H 5.44,
52CAHTREUNGH48ACHTERUNNG 4ACHTRENUOG 6ACHTREUNG
N 6.30; found: C 70.12, H 5.44, N 6.31.
S,S’-{[4,9-Bis({[4-(1,1-dimethylethyl)phenyl]methyl}sulfanyl)-1,3,6,8-tetrahydro-1,3,6,8-tetraoxoben-
zo[lmn][3,8]phenanthroline-2,7-diyl]dibenzene-4,1-diyl} Diethanethioate (5). To a soln. of 18 (0.1260 g,
0.132 mmol) in CH2Cl2 (25 ml), toluene (5 ml), and AcCl (10 ml), a soln. of BBr3 in CH2Cl2 (0.5 ml)
was added dropwise at 08. The mixture was stirred for 1 h at r.t., poured into H2O, and extracted with
CH2Cl2. The combined org. phases were concentrated at reduced pressure, and the residue was purified
by CC (SiO2; CH2Cl2/AcOEt 1:0 ! 20 :1). Yield: 0.0801 g (65%). Red solid. M.p. 313–3158. UV/VIS
(CH2Cl2): 528 (21100), 493 (11500), 370 (14400), 355 (12000), 297 (59800), 265 (29900). Fluorescence
1
spectrum (CH2Cl2): lmax 558 nm. H-NMR (CDCl3, 508): 1.29 (s, 6 Me); 2.46 (s, 2 Me); 4.37 (s, 2 CH2);
7.33 (d, 3J=8.4, 4 H); 7.36–7.42 (m, 8 H); 7.61 (d, 3J=8.7, 4 H); 8.87 (s, 2 H). 13C-NMR (C
2ACTHREDUNG 2Cl4):

2004
Helvetica Chimica Acta – Vol. 89 (2006)
30.62; 31.37; 34.61; 37.17; 118.95; 124.10; 125.46; 126.12; 128.89; 129.16; 129.53; 129.60; 130.83; 135.14;
135.25; 149.36; 151.27; 162.16; 163.22; 193.31. MALDI-TOF-MS: 921.3207 (M+, C S4þ ; calc.
52A 46A 2A 6A
CTHREUNGH CHTREUNGN CHTREUNGO CHTREUNG
922.2233). Anal. calc. for C52H46N2O6S4 (923.18): C 67.65, H 5.02, N 3.03; found: C 67.48, H 5.07, N 3.12.
S,S’-{[4,9-Bis({[4-(1,1-dimethylethyl)phenyl]methyl}selanyl)-1,3,6,8-tetrahydro-1,3,6,8-tetraoxoben-
zo[lmn][3,8]phenanthroline-2,7-diyl]dibenzene-4,1-diyl} Diethanethioate (6). To a soln. of 19 (0.0666 g,
0.064 mmol) in CH2Cl2 (10 ml), toluene (4 ml), and AcCl (4 ml), a soln. of BBr3 in CH2Cl2 (0.2 ml)
was added dropwise at 08. The mixture was stirred for 1 h at r.t., poured into H2O, and extracted with
CH2Cl2. The combined org. phases were concentrated at reduced pressure, and the residue was purified
by CC (SiO2; CH2Cl2). Yield: 0.0387 g (59%). Pink solid. M.p. 320–3228. UV/VIS (CH2Cl2): 553 (23400),
1
515 (13000), 375 (20700), 357 (17100), 308 (51700). Fluorescence spectrum (CH2Cl2): lmax 594 nm. H-
NMR (C
H); 7.65 (d, 3J=7.8, 4 H); 8.90 (s, 2 H). 13C-NMR (C
125.25; 127.69; 128.13; 130.77; 131.26; 131.34; 132.94; 133.58; 136.69; 136.97; 149.04; 152.49; 163.92;
165.53; 194.67. MALDI-TOF-MS: 1016.4682 (M+, C Se2þ ; calc. 1016.1145). Anal. calc. for
52A 46A 2A 6A 2A
D2Cl4, 508): 1.32 (s, 6 Me); 2.52 (s, 2 Me); 4.34 (s, 2 CH2); 7.38 (s, 8 H); 7.43 (d, 3J=7.8, 4
2ACHTREUNG
2ACHTRENUDG 2Cl4, 508): 32.18; 32.67; 33.03; 36.23; 123.00;
CTHREUNGH THCREUNGN CHTREUNGO CHTRNUGSE CHTREUNG
C52H46N2O6S2Se2 (1016.98): C 61.41, H 4.56, N 2.75; found: C 61.23, H 4.61, N 2.96.
S,S’-{[4-({[4-(1,1-Dimethylethyl)phenyl]methyl}amino)-9-({[4-(1,1-dimethylethyl)phenyl]methyl}sul-
fanyl)-1,3,6,8-tetrahydro-1,3,6,8-tetraoxobenzo[lmn][3,8]phenanthroline-2,7-diyl]dibenzene-4,1-diyl}
Diethanethioate (7). To a soln. of 20a (0.2352 g, 0.252 mmol) in CH2Cl2 (20 ml), toluene (5 ml), and AcCl
(10 ml), a soln. of BBr3 in CH2Cl2 (1 ml) was added dropwise at 08. The mixture was stirred for 1 h at r.t.,
poured into H2O, and extracted with CH2Cl2. The combined org. phases were concentrated at reduced
pressure, and the residue was purified by CC (SiO2; CH2Cl2/AcOEt 1:0 ! 20 :1). Yield: 0.1380 g
(60.5%). Violet solid. M.p. 298–2998. UV/VIS (CH2Cl2): 567 (24300), 529 (14500), 366 (14600), 351
1
(13600), 289 (48700), 274 (45900). Fluorescence spectrum (CH2Cl2): lmax 596 nm. H-NMR (C
2A
3
1.31 (s, 3 Me); 1.32 (s, 3 Me); 2.51 (s, Me); 2.53 (s, Me); 4.19 (s, SCH2); 4.63 (d, J=5.1, NCH2); 7.31
(d, J=8.4 2 H); 7.34–7.43 (m, 8 H); 7.46 (d, 3J=8.4, 2 H); 7.59 (d, J=8.4, 2 H); 7.62 (d, 3J=8.4, 2
3
3
3
H); 8.30 (s, 1 H); 8.56 (s, 1 H); 9.98 (t, J=5.1, NH). 13C-NMR (C
D2Cl4): 32.29; 32.32; 33.07; 33.08;
36.28; 38.64; 48.98; 102.26; 121.06; 122.12; 123.06; 124.96; 127.70; 127.92; 128.22; 128.71; 129.28;
129.82; 130.81; 130.87; 131.01; 131.34; 131.47; 132.86; 134.68; 136.81; 136.87; 137.06; 137.53; 145.82;
152.68; 152.73; 152.99; 163.86; 164.35; 165.09; 167.53; 195.04; 195.21. Anal. calc. for
C52H47N3O6S3 ·H2O (924.16): C 67.58, H 5.34, N 4.55; found: C 67.82, H 5.50, N 4.39. MALDI-TOF-
MS: 904.1173 (M+, C Sþ3 ; calc. 905.2622).
52CAHTREUNGH47ACHTERUNNG 3ACHTRENUOG 6ACHTREUNG
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Received May 15, 2006