Triazole linked ruthenium(II)-porphyrin: Influence of the connectivity pattern on photophysical and electrochemical properties

Article abstract of DOI:10.1039/c6nj01676f

Herein a copper catalysed click reaction has been used to covalently link π-conjugated 1,2,3-triazolyl zinc(ii) porphyrin and ruthenium(ii) bipyridyl with a single change in their connection through the linker. The properties of these compounds have been compared with the porphyrin-ruthenium(ii) tris(bipyridine) and ruthenium(ii) trisbipyridine complexes. Extensive photophysical and electrochemical studies reveal that changes in the electronic properties of the conjugates are a consequence of the different connectivity patterns with regular and inverse triazolyl-pyridyl moieties.

Full text of DOI:10.1039/c6nj01676f

View Article Online
View Journal
NJC
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: S. Arora, R.
Nagpal, P. Chauhan and S. M.S. Chauhan, New J. Chem., 2016, DOI: 10.1039/C6NJ01676F.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/njc

Please do not adjust margins
New Journal of Chemistry
Page 1 of 9
View Article Online
DOI: 10.1039/C6NJ01676F
Journal Name
ARTICLE
Triazole linked Ruthenium(II) porphyrin: Influence of connectivity
pattern on photophysical and electrochemical properties
Received 00th January 20xx,
Accepted 00th January 20xx
Smriti Arora, Ritika Nagpal, Prashant Chauhan, Shive Murat Singh Chauhan*
DOI: 10.1039/x0xx00000x
Herein copper catalysed click reaction has been used to covalently link π-conjugated 1,2,3-triazolyl zinc(II) porphyrin and
ruthenium(II) bipyridyl with a single change in their connection through the linker. The properties of these compounds
have been compared with the porphyrin–ruthenium(II) tris(bipyridine) and ruthenium(II) trisbipyridine complexes.
Extensive photophysical and electrochemical studies reveal the changes in electronic properties of the conjugates are a
consequence of the different connectivity patterns with regular and inverse triazolyl-pyridyl moieties.
www.rsc.org/
several functional ligands for coordination complexes.8 1,2,3ꢀtriazole
moiety, a heterocyclic linking unit is considered to be a premier
example capable of coordinating to metal centers in a variety of
modes. 1,2,3ꢀtriazole has been proved to be a versatile conjugative
Introduction
In natural photosynthetic systems, porphyrinꢀbased complex serves
as the photoactive unit which captures sunlight.1 To mimic the
natural photosynthetic solar energy transduction process, several
synthetic porphyrins with large absorption coefficients,
multicomponent photoactive arrays in covalent or noncovalent forms
have been designed.2 These mimics incorporate an electron donor,
an electron acceptor, and a bridging unit.3 The donor in many of
these systems is a porphyrin or phthalocyanine due to its excellent
photophysical and electrochemical properties. The electron acceptor
in many model systems is based on Re(I), Ru(II), Os(II), and Cr(III)
complexes.4 Among these, Re(I) and Ru(II), which exhibit highꢀ
energy luminescent levels, usually play the role of photosensitizers.
The third important unit is linker connecting the two chromophores
πꢀlinker to covalently connect two choromophores such as
porphyrinꢀfullerene,9 porphyrinꢀgraphene,10 porphyrinꢀporphyrin.11
In particular, the copperꢀcatalyzed azideꢀalkyne cycloaddition
(CuAAC) has been used in the synthesis of dendronized linear
polymers containing photoactive molecules and in the
functionalization of the surface of singleꢀwall carbon nanotubes with
polystyrene to solubilize them in a variety of organic solvents.12
These examples represent interesting applications in molecular
electronics, which show the deliberate replacement of bipyridyl with
triazolylꢀpyridyl13 should impose interesting electronic properties of
the 1,2,3ꢀtriazole in the porphyrinꢀruthenium(II) macrocycles.14 In
this paper, we have selectively synthesized 1,4ꢀdisubstituted 1,2,3ꢀ
triazoles15 with a change in mode of connection at 1 and 4 position
of triazole giving rise to two different chelators. These chelators
were complexed with ruthenium bipyridyl unit to obtain the desired
donorꢀacceptor conjugates. The one coordinating through the more
electron rich N3 nitrogen atom of 1,2,3ꢀtriazole is a regular triazolylꢀ
pyridyl complex while the one coordinating via N2 nitrogen atom is
an inverse triazolylꢀpyridyl complex. In order to gain more insight of
structureꢀproperty relationship, photophysical and electrochemical
studies were performed to check the applicability of the novel
conjugates.
as mixing
a solution of donor and acceptor at micromolar
concentrations does not lead to any significant electronic interactions
as no efficient quenching of the donor excited state was observed.
While introducing a linker between the two units, has a drastic effect
on the electron and energy transfer rates of the system.
Supramolecular species (molecular dyads, triads, and tetrads)
consisting of metalloporphyrin and ruthenium polypyridine
complexes are currently the objective of extensive investigations, as
they provide rich photophysical properties which stems from the
increase in light harvesting capability as they provide an extentded
absorption range favorable for the collection of light.5 Analogous
motifs with improved photophysical and electrochemical properties
can be successfully designed by finelyꢀtuning the substituents on
porphyrin, nature of the bridge connecting porphyrin and ruthenium
chromophores. Previous reports have shown covalent linkage of
porphyrin with ruthenium(II) bipyridyl using amide as a linker.6,7
Results and Discussion
Synthesis and Characterization
Copper(I)ꢀcatalyzed azideꢀalkyne click reaction regioselectively
gives 1,4ꢀdisubstitutedꢀ1,2,3ꢀtriazole ring. The clicked ligands 2
(inverse triꢀpy), 7 (regular triꢀpy) were synthesized from their
corresponding meso substituted (pꢀalkynyl or pꢀazido phenyl)
porphyrins as shown in Scheme 1. Since, lipid insolubility and
aggregation seems to be the major factor in decreasing the efficiency
of photosensitizer, 3,5ꢀdiꢀtertꢀbutylphenyl groups have been
introduced at meso positions of the porphyrin ring.16
Click chemistry is a widely defined tool used for creating
The monoꢀalkynyl porphyrin was synthesized by mixedꢀ
aldehyde
condensation
using
4ꢀ(Trimethylsilylꢀ
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 2 of 9
View Article Online
DOI: 10.1039/C6NJ01676F
ARTICLE
Journal Name
1
ethynyl)benzaldehyde and 3,5ꢀdiꢀtertꢀbutylbenzaldehyde with ppm in 8ꢀZn. Complete H NMR are shown in supplementary data
pyrrole in dichloromethane under an argon atmosphere using (Figure S8,S16) while partial NMR are presented in Figure 1. The
catalytic amount of boron trifluoride diethyletherate afforded the assignment of peaks in the 1H NMR spectrum of conjugates was
porphyrinogen, which was oxidized to the corresponding porphyrin aided by COSY NMR spectrum (Figure 2). Different pattern for βꢀ
using 2,3ꢀdichloroꢀ5,6ꢀdicyanoꢀ1,4ꢀbenzoquinone (DDQ). The porphyrinic protons was observed for metallated and base free
protecting
group
trimethylsilyl
was
removed
with conjugates which may be attributed to different orientations of the
tetrabutylammonium fluoride (TBAF) to yield alkynylporphyrin (1) two compounds.
and zinc(II) was inserted into the porphyrin using Zn(OAc)2 in
chloroform:methanol. The CuAAC between alkynylporphyrin and 2ꢀ
azidopyridine was performed in the presence of copper sulphate,
sodium ascorbate, DIPEA, CH2Cl2/EtOH/H2O refluxed at 50 °C
afforded the inverse triazolylꢀpyridyl porphyrin 2ꢀZn in 85% yield.17
2Cl-
N
Ru
N
+2
N
N
N
N
N
N
N
N
N
N
N
(Scheme 1)
Ru(bpy)2Cl2
THF/Ethanol
N
N
N
N
M
M
N
N
N
800
C
The synthesis of pꢀazidophenylporphyrin (6) also utilized the
(3)
(2)
M=Zn, 2H
Lindsey
mixedꢀaldehyde
method,
with
substituting
pꢀ
acetamidobenzaldehyde
for
ethynylbenzaldehyde.18
The
2Cl-
deacetylation of 4 in presence of EtOH/HCl gave 4ꢀaminoꢀ3,5ꢀdiꢀ
tert-butylphenylporphyrin (5)19 which was diazotized by reaction
with TFA/NaNO2, followed by in situ treatment with NaN3 to give
4ꢀazidoꢀ3,5ꢀdiꢀtert-butylphenylporphyrin (6).9a The porphyrin was
clicked7a in the presence of copper sulphate, sodium ascorbate,
DIPEA, CH2Cl2/EtOH/H2O refluxed at 50 °C afforded with 2ꢀ
ethynyl pyridine to afford triazolylꢀpyridyl porphyrin 7ꢀZn in 85%
yield. (Scheme 1)
N
N
N
N
N
+2
Ru
N
N
N
N
N
N
N
N
Ru(bpy)2Cl2
THF/Ethanol
N
M
N
M
N
N
N
N
N
800
C
(7)
M=Zn, 2H
.Scheme 2: Synthetic route for Ru(II) bidentate complexes
NH
N
N
N
N
N
N
N
a) Metallation
N
N
H
M
b) Click Reaction
N
HN
(2)
(1)
N
N
3
M=Zn, 2H
a) Metallation
NH
N
N
N
N
N
N
b) Click Reaction
3
M
N
N
HN
N
N
N
(7)
(6)
N
M=Zn, 2H
Scheme 1: Synthetic route for chelators: 2ꢀ[4ꢀporphyrinylꢀ1Hꢀ1,2,3ꢀ
triazolꢀ1ꢀyl]pyridine (2,2ꢀZn, inverse triꢀpy) and 2ꢀ[1ꢀporphyrinylꢀ
1Hꢀ1,2,3ꢀtriazolꢀ4ꢀyl]pyridine (7,7ꢀZn, regular triꢀpy)
The click reaction of free base alkyne porphyrin (1) and azido
porphyrin (6) gave the corresponding 1,2,3ꢀtriazole in low yield.
Therefore, the metal free conjugates were synthesized by removal of
zinc metal from triazolyl porphyrin 2ꢀZn and 7ꢀZn under mildly
acidic conditions at room temperature in 90% yield.20
Heteroleptic triazole chelators on refluxing with a requisite
stoichiometry of cisꢀdichlorobis(2,2'ꢀbispyridyl)ruthenium(II) in
EtOH/THF gave the corresponding octahedral complex in ~20%
yield.21 (Scheme 2)
Figure 1: 1H NMR spectrum of 3ꢀZn, and 8ꢀZn in Methanolꢀd
The formation of Ru(II)ꢀoctahedral complexes were apparent
from the three resonance signals in 1H NMR at δ 1.5 ppm (tertꢀbutyl
H), 7.96ꢀ7.33 ppm (bipyridyl H), a triazole H singlet at 8.42 ppm in
3ꢀZn and 8.52 ppm in 8ꢀZn (shifted upfileld as compared to the
triazolyl porphyrin), βꢀpyrrolic H’s at 8.74 ppm in 3ꢀZn and 8.84
1,2,3ꢀtriazoles have proved to show interesting hydrogen
bonding due to their large polarity (dipole moment ∼5D), with the
positive end of the dipole situated at the CH group.22 The triazolylꢀ
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 3 of 9
View Article Online
DOI: 10.1039/C6NJ01676F
Journal Name
ARTICLE
pyridyl ligand (7) shows intramolecular Hꢀbonding (triazoloꢀ4H and (bpy πꢀπ*) were observed which were blue shifted in 3 as compared
PyꢀN) in nonꢀpolar solvent replaced by ligandꢀsolvent Hꢀbonding in to 8. In 8, 8ꢀZn, the metal to ligand charge transfer absorptions
polar solvent as depicted by the downfield shift in 1H NMR, around 450 nm associated with the peripheral ruthenium complexes
bathochromic shift in UV visible spectra on addition of MeOH indicate energy transfer from [Ru(bpy)2Cl]+ triplet states to the
(Figure S28).
lowest energy triplet state of the zinc porphyrin, while in 3, 3ꢀZn
relatively low intensity band is observed. This conclusion is
supported by the fact that the emission spectrum obtained by
excitation at 450 nm, i.e. in the MLCT band of the ruthenium
complexes, exhibits essentially the strongly quenched porphyrin
emission.24,25 However, the weaker MLCT band in 3ꢀZn shows a
weaker electronic communication in ground state between ruthenium
bipyridyl and porphyrin moiety.
a)
Figure 2: COSY spectrum of 8ꢀZn in Methanolꢀd
The structure was further confirmed by MALDIꢀTOF mass
spectrometery which shows loss of neutral ligands, charge reduction,
and association with a counterion, in addition to the peaks from Zn
triazolylꢀpyridyl porphyrin (Figure 3). Fragmentation proceeds with
loss of Zn which is rarely observed, indicating that demetalation is
affected by the linker as well as the substituents on the porphyrin
ring.23
b)
Figure 4: UV visible spectra a) 2ꢀZn, 3ꢀZn (2.4*10ꢀ6M); 7ꢀZn,8ꢀZn
(4.0*10ꢀ6M) and fluorescence (λmax= 420 nm) b) 2ꢀZn, 3ꢀZn (2.4*10ꢀ
6M); 7ꢀZn,8ꢀZn (4.0*10ꢀ6M) spectra of ruthenium(II)ꢀporphyrin
conjugates
The relative emission profile of the metallated dyad 3ꢀZn is
strongly quenched to about 80 %, 40 % when excited at 420 nm and
550 nm, with respect to the triazole porphyrin 2ꢀZn (Table 1). The
data show that the electron transfer occurs to a much higher extent in
3ꢀZn as compared to other conjugates. These results are in
agreement with the fluorescence quantum yields. Similar results are
observed with 7ꢀZn, 8ꢀZn as well. A significantly higher quenching
when excited at 420 nm, Soret band, proves that only half of the S2
population gets back to S1, while the other half goes via. different
pathway. Hence, the emission and absorption profile comparison
demonstrates efficient electronic communication in the excited state
while no groundꢀstate interaction between porphyrin and ruthenium
bipyridyl is observed.
Figure 3: MALDIꢀTOF mass spectrum of 8ꢀZn
Photophysical Properties
Figure 4 depicts ground state absorption spectra of the four
ruthenium(II)ꢀporphyrin complexes in dichoromethane under
ambient conditions. The free base porphyrinꢀruthenium(II)
conjugates, show intense Soret band (S0→S2 transition) ~ 424 nm
and four Q bands ~ 500ꢀ700 nm (S0→S1 transition), respectively.
Introduction of a Zn (II) ion to the porphyrin conjugate, results in
small red shift of the Soret band and the number of Q bands were
reduced from four to two. In addition to this typical pattern,
absorption bands from ruthenium bipyridyl moiety ~ 285ꢀ295 nm
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 4 of 9
View Article Online
DOI: 10.1039/C6NJ01676F
ARTICLE
Journal Name
Table 1: Steadyꢀstate emission spectroscopic properties of 2ꢀ[1ꢀporphyrinylꢀ1Hꢀ1,2,3ꢀtriazolꢀ4ꢀyl]pyridine, 2ꢀ[4ꢀporphyrinylꢀ1Hꢀ1,2,3ꢀ
triazolꢀ1ꢀyl]pyridine and its ruthenium complexes.
d
e
Entry
λabs (nm)
λema/nm
λemb/nm
λemc/nm
Φem
Фem
(Int./a.u.)
(Int./a.u.)
(log ε)
(Int./a.u.)
2
422(5.48),
519(4.08),
556(3.78),
594(3.68),
650 (3.62).
653(102.2),
719(26.5)
ꢀ
653 (4.46),
719 (1.22)
0.00093
0.048
2ꢀZn
3
426(5.38),
553(4.25),
597 (3.50)
604(31.47),
651 (21.22)
ꢀ
605 (3.30),
651 (1.89)
0.00055
0.00059
0.059
0.036
288(4.63),
424(5.42),
520(4.02),
555(3.80),
594(3.51),
650 (3.48)
652 (57.69),
719(14.06)
654 (0.65),
719 (0.17)
653 (2.78),
719 (0.70)
3ꢀZn
7
286 (4.70),
427 (5.31),
554 (4.10),
598 (3.60)
604(5.04),
652(3.96)
606 (0.12),
654 (0.098)
604 (1.67),
655 (1.20)
0.000115
0.0027
0.039
0.174
424(5.57),
520(4.05),
557(3.75),
595(3.68),
651(3.66)
652(11.15),
719(3.23)
ꢀ
655(0.34),
720(0.11)
7ꢀZn
8
426(5.29),
553(3.92),
598(3.60)
596(31.2),
648(36.1)
597(3.09),
647(3.11)
0.00033
0.0023
0.043
0.137
295(4.71),
425(5.53),
521(4.05),
556(3.67),
596(3.60),
651(3.66)
653(9.45),
719(2.20)
656(1.26),
719(0.35)
655(0.28),
720(0.11)
8ꢀZn
290(4.81),
427(5.26),
552(4.0),
598(3.89)
597(12.7),
647(11.6)
600(0.08),
652(0.10)
598(2.84),
647(2.41)
0.00017
0.0406
aλex = 420 nm, bλex = 450 nm, cλex = 550 nm, dEmission quantum yields (λem = 550ꢀ800 nm, λex = 420 nm), eEmission quantum yields (λem
= 560ꢀ800 nm, λex = 550 nm), Emission quantum yields are measured with ZnTPP as standard.
The inverse (3, 3ꢀZn) and regular (8, 8ꢀZn) complexes show
different stability towards sunlight. Acetonitrile solutions of both
the complexes were monitored by UV visible spectroscopy. The
intensity of Soret band due to porphyrin decreases slowly while the
absorption band for Rubpy moiety persists for 3, 3ꢀZn when kept
in sunlight for more than 24 hours while no changes in UV visible
were observed for 8, 8ꢀZn over the same time period. Interestingly,
no changes in the absorption spectrum were observed for the same
complexes kept in dark. Thus, complexes even being structurally
same but ligand exchange studies indicate the regular Ru(II)ꢀtripy
complex are more stable than their inverse analogues. These results
are
consistent
with
previously
performed
studies.26
.
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 5 of 9
View Article Online
DOI: 10.1039/C6NJ01676F
Journal Name
ARTICLE
Electrochemistry
The redox properties of metal free triazole porphyrinꢀruthenium
bipyridyl conjugates (3, 8), their zinc counterparts (3ꢀZn, 8ꢀZn)
were studied by means of cyclic voltammetry in anhydrous
dichloromethane
using
tetraꢀnꢀbutylammonium
hexafluorophosphate (TBAPF6) as the supporting electrolyte and
ferrocene/ferrocinium (Fc/Fc+) as the internal reference, platinum
wire as counter electrode, glassy carbon electrode as working
electrode (~0.25 cm2), and Ag/Ag+ as reference electrode,
respectively. The halfꢀwave potentials, E1/2, were determined as
(Epa + Epc)/2, where Epa and Epc are the anodic and cathodic peak
potentials determined from the CV measurements are given in
Table 2 alongwith redox potentials of the related compounds.
In the investigated chemical window (ꢀ2.0 to 2.0 V) a reversible
cyclic voltagram is observed for all the four compounds. The
electrochemical response of 3ꢀZn (Figure 5), 8ꢀZn (Figure S26)
show four reversible oxidation peaks ranging from 0.40 V to 1.60
V vs SCE which were anodically shifted between 0.63 V to 1.50 V
in the case of metal free counterparts 3, 8 (Figure S27). The first
two oxidation peaks correspond to the oxidation of ZnP while the
fourth peak is assigned to metalꢀbased oxidation (Ru2+/Ru3+)
couple making the
Figure 5: Cyclic voltammogram (CV) of 8ꢀZn, 3ꢀZn in
CH2Cl2(2*10ꢀ3 M) with a scan rate of 50 mV/s (0.1 MTBAPF6)
Table 2. Electrochemical data versus SCE for complexes and model compounds
Entry
invꢀpytri
Ist Oxid.
1.40
IInd Oxid.
IIIrd Oxid.
IVth Oxid. Ist Red.
IInd Red.
ꢀ1.43
IIIrd Red. aBand Gap (Eg)
b
b
b
ꢀ1.24
ꢀ1.79
2.64
1.68
1.73
1.51
2.60
1.58
1.67
1.26
2.67
1.57
b
b
b
2ꢀZn
3
0.75
0.63
0.54
1.32
0.81
0.68
0.40
1.30
0.78
1.15
0.74
ꢀ0.93
ꢀ1.66
ꢀ1.55
ꢀ1.26
ꢀ1.49
ꢀ1.29
ꢀ1.55
ꢀ1.54
ꢀ1.51
ꢀ1.07
b
b
1.08
1.35
b1.60
ꢀ1.10
ꢀ0.97
ꢀ1.28
ꢀ0.77
ꢀ0.99
ꢀ0.86
ꢀ1.32
ꢀ0.79
3ꢀZn
regꢀpytri
7ꢀZn
8
0.87
b
1.32
b
b
ꢀ1.96
b
b
b
b
b
1.12
1.16
b
b
8ꢀZn
0.74
b
1.16
b
c1.46
b
Ru(bpy)3
Ruꢀamide23
ꢀ1.76
ꢀ1.43
b
1.17
1.68
ZnꢀPorphyrin
aCalculated by difference of HOMO and LUMO, all the spectra are measured in CH2Cl2; HOMOꢀLUMO: ꢁE = E1st oxidation ꢀE1st
reduction; b Peaks donot appear; c irreversible peak
complex to facilitate electron/energy transfer by generation of
porphyrin πꢀcation radical upon photoexcitation of the Ru subunit.
Whereas reduction peaks at E1/2 = ꢀ0.86 V, ꢀ1.54 V in 8ꢀZn were
observed showing that stepwise electrode processes occur between
the bipyridyl ligands and ZnP units of the 8ꢀZn complex. Similarly
for zinc free counterpart, 8 reversible reduction peaks at ꢀ0.99 V, ꢀ
1.55 V were observed.
triazolylꢀpyridyl complexes 3, 3ꢀZn shows a cathodic shift of 220
mV, 210 mV for E°red1. The effect of a regular triazole ligand 8, 8ꢀ
Zn is a large cathodic shift of 330 mV, 460 mV for E°red1. This
shift indicates that the conjugates 3, 3ꢀZn are slightly harder to
reduce than the compounds in which porphyrin is connected to the
nitrogen of the triazole ring. Hence, the reducability sequence for
the porphyrins is 3ꢀZn>3>8>8ꢀZn>Ru(bpy)3 for the first reduction
process. These results are consistent with the poorer electron
donating ability than their regular analogues.26
Electrochemistry in dichoromethane changes with ligand
variation in regular ruthenium(II) complexes (Table 2).
Synthesized porphyrinꢀruthenium(II) complexes are comparatively
easy to reduce as compared to archetypal Ru(bpy)3. Considering
the structure of porphyrin complexes synthesized, the inverse
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 6 of 9
View Article Online
DOI: 10.1039/C6NJ01676F
Journal Name
ARTICLE
Replacement of a bipyridyl unit with triazolylꢀpyridyl results in
Synthesis
2- 5-(4-phenyl)-10,15,20-tris(3,5-di-tert-butylphenyl)porphyrinato
a smaller HOMO/LUMO energy gap as observed in 3ꢀZn, 8ꢀZn
compared to
a
previously reported ZnꢀRuamide27 species.
[
HOMO/LUMO band gap variation also goes along with the
differences in the ground state conjugation depending on the
connectivity pattern at triazole. When ZnP is attached directly to the
triazole N, ground state conjugation is interrupted as the charge
transfer resonance structure has cationic character due to the
zinc]-1H--1,2,3-triazol-1-yl pyridine (2ꢀZn)
Porphyrin 1 was metallated by dissolving zinc acetate (0.18 g, 0.83
mmoles) in 1:1 MeOH/CHCl3 (50 mL), reaction was refluxed for 1 h
and the crude mixture was washed three times with water. The
organic layer was dried over Na2SO4 and filtered. Zn alkyne
porphyrin (311 mg, 0.319 mmoles) was added to a mixture of
pyridyl azide (35 mg, 0.291 mmoles), CuSO4.5H2O (11.25 mg,
543.83 mmoles), sodium ascorbate (18.03 mg, 432.19 mmoles),
DIPEA (117.91 ꢂL, 282.62 mmoles) in DCM/H2O/EtOH (5:2:1) (60
formation of
a quaternary ammonium centre. A narrower
HOMO/LUMO gap in 8, 8ꢀZn as compared to 3, 3ꢀZn, is observed
which would increase the electronic coupling, thus, increasing the
charge transfer in conjugates. In general a linear increase in HOMOꢀ
LUMO gap with the donorꢀacceptor distance has been observed.9b
mL) and stirred at 50
℃ for 12 h. After cooling, the reaction mixture
was diluted with CH2Cl2 (20 mL) and washed with water. The
resulting organic layer was dried over Na2SO4 and evaporated to
dryness. The residue was purified by silica gel coloumn
chromatography using 7:3 CHCl3/petroleum ether as eluent to yield
the desired product in 85% yield (0.314 g).
A
smaller band gap is observed for the zincꢀmetallated
conjugates compared to their unmetallated counterparts, 8ꢀZn (Eg =
1.26 eV) compared to 8 (Eg = 1.67 eV), in agreement with the red
shift of the absorption spectrum.17 All these observations show that
type of linker and metal has an important influence on the LUMO
energy level.28
Rf : 0.5 (CHCl3); UV−visible (CHCl3), λabs/nm (log ε): 426 (5.38),
Conclusions
1
553 (4.25), 597
(3.50); H NMR (400 MHz, Chloroformꢀd) δ
ppm 9.1ꢀ8.95 (m, 8H, βH), 8.59 (s, triazole H, 1H), 8.38ꢀ8.30 (m,
5H, ArH, PyH), 8.10 (m, 6H, ArH), 8.00 (t, 1H, PyH), 7.78 (s, 3H,
ArH), 7.42 (t, 1H, PyH), 1.51 (s, 54H, tꢀbutyl); 13C NMR (100 MHz,
Chloroformꢀd) δ ppm: 150.5, 150.5, 150.3, 148.6, 143.4, 141.9
139.4, 135.0, 132.5, 132.3, 132.2, 131.7, 129.8, 129.7, 124.2, 122.5,
120.8, 117.2, 115.9, 114.0, 35.1, 31.7; MALDI calculated 1156.5797
(C75H82N8Zn), observed 1095.6741 (MꢀZn+H)+, 1067.9371 (MꢀZnꢀ
N2).
Clicked triazole porphyrin ligands 7, 7ꢀZn and their corresponding
heteroleptic Ru(II) conjugates 8, 8ꢀZn with electron donor and
acceptor fragments were synthesized. Triazolyl group acts as a
bridging framework for interesting photoꢀinduced electron or energy
transfer process between porphyrin and Ru bpy. The properties of
these inverse and regular complexes have been compared with
Ru(bpy)3 and previously reported porphyrin ruthenium complexes.
Photophysical and electrochemical studies clearly demonstrates that
the energies of the orbital in the conjugates depend on (1)
ligand/linker, (2) connecting pattern of linker, (3) the presence of Zn
metal ion in the porphyrin core. Though structurally same but ligand
exchange studies indicate the regular Ru(II)ꢀtripy complex are more
stable than their inverse analogues. The change in linker provides
new insights for the design of more efficient sensitizers for dye
sensitized solar cells and optoelectronic devices.
2-[5-(4-phenyl)-10,15,20-tris(3,5-di-tert-butylphenyl)porphyrinato
zinc]-1H-1,2,3-triazol-1-yl-pyridine 2,2'-bispyridine ruthenium(II)
chloride (3ꢀZn)
Porphyrin (2ꢀZn) (0.030 g, 0.0258 mmoles) and cisꢀRu(bpy)2Cl2 (6)
(37 mg, 0.077 mmol) were added in a mixture of THF (8 mL) and
EtOH (8 mL). The solution was bubbled with N2 for a few minutes,
and heated to 85 °C. After refluxing for 15 h, the solvent was
removed under vacuum to dryness. The residue was
Experimental
The IR spectra were recorded on a Perkin Elmer 1710 FTIR chromatographed on neutral Al2O3. Brown coloured band was
spectrometer and the νmax was expressed in cmꢀ1. The absorption
collected using CHCl3:MeOH (v/v) = 10:1 as eluent to give 3ꢀZn in
20 % yield (8.54 mg).
spectra were recorded on a Perkin Elmer Lambdaꢀ35 UV/Vis
spectrophotometer and the
λ
max was expressed in nanometers. The 1H
Rf : 0.3 (10% MeOH : CHCl3); UV Vis. (CHCl3), λabs/nm (log ε):
1
NMR spectra were recorded on Bruker Avanceꢀ400 spectrometer
using TMS as internal standard (chemical shifts in ppm).
Fluorescence spectra were recorded on Varian Cary fluorescence
spectrometer. MALDI Spectra were recorded on MS ꢀ ABI Sciex
5800 TOF/ TOF System with LCꢀMALDI in cinnamic acid matrix.
ESIꢀMS spectra were recorded on Agilent Technologies 6530
AccurateꢀMass QꢀTOF LC/MS. Cyclic voltammograms of the
samples were obtained using CHI 600D electrochemical analyzer.
The compounds were purified using silica gel (60ꢀ120 mesh), neutral
alumina chromatography.
286 (4.70), 427 (5.31), 554 (4.10), 598 (3.60); H NMR (400 MHz,
Metahnolꢀd) δ ppm : 8.76ꢀ8.65 (m, 10H, βH, PyH), 8.69ꢀ8.55 (m,
2H, Py H), 8.42 (s, 1H, triazole H), 8.18ꢀ8.15 (m, 2H, ArH), 8.10ꢀ
8.00 (m, 4H, ArH, PyH), 8.0ꢀ7.9 (m, 8H, ArH, PyH), 7.83ꢀ7.7 (m,
8H, ArH, Py H), 7.65ꢀ7.62 (d, 1H, PyH), 7.58ꢀ7.41 (m, 5H, PyH),
7.38ꢀ7.31 (m, 1H, PyH), 1.51 (s, 54 H, tꢀbutyl); MALDI: calculated
1640.5593
(C95H96Cl2N12RuZn),
observed
1543.6771
[(Ru(2)(bpy)2]+Cl.
2-[5-(4-phenyl)-10,15,20-tris(3,5-di-tert-butylphenyl)porphyrinyl]-
1H-1,2,3-triazol-1-yl pyridine (2)
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 6
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 7 of 9
View Article Online
DOI: 10.1039/C6NJ01676F
Journal Name
ARTICLE
Porphyrin (2ꢀZn) (0.050 g, 0.043 mmoles) in CH2Cl2 (15 mL) was 118.4, 35.0, 31.7; MALDI: calculated 1156.5797 (C75H80N8Zn),
added HCl in dioxane (20 M, 2.5 mL), stirred at r.t. for 5 min. The observed 1094.6662 (7ꢀZn), 1066.6601 (7ꢀN2).
mixture was neutralised with saturated NaHCO3 solution, dried over
sodium sulphate, and the solvent was removed under reduced
pressure to yield the product in 90% yield (0.045g).
2-[5-(1-phenyl)-10,15,20-tris(3,5-di-tert-butylphenyl)porphyrinato
zinc]-1H-1,2,3-triazol-4-yl-pyridine 2,2'-bispyridine ruthenium(II)
chloride (8ꢀZn)
Rf : 0.5 (CHCl3); UV−visible (CHCl3), λabs/nm (log ε) 422 (5.48),
1
519 (4.08), 556 (3.78), 594 (3.68), 650 (3.62); H NMR (400 MHz,
Porphyrin (7ꢀZn) (0.030 g, 0.0258 mmoles) and cisꢀRu(bpy)2Cl2 (6)
(37 mg, 0.077 mmol) were added in a mixture of THF (8 mL) and
EtOH (8 mL). The solution was bubbled with N2 for a few minutes,
and heated to 85 °C. After refluxing for 15 h, the solvent was
removed under vacuum to dryness. The residue was
chromatographed on neutral Al2O3. Brown coloured band was
collected using CHCl3:MeOH (v/v) = 10:1 as eluent to give 8ꢀZn in
19 % yield (8.09 mg).
Chloroformꢀd) δ ppm 9.1ꢀ8.85 (m, 8H, βH), 8.60 (s, 1H, triazole H),
8.40ꢀ8.32 (m, 5H, ArH, PyH), 8.15ꢀ8.06 (m, 6H, ArH), 8.00 (t, 1H,
PyH), 7.80 (s, 3H, ArH), 7.42 (t, 1H, PyH), 1.51 (s, 54H, tꢀbutyl), ꢀ
2.40 (s, 2H, ꢀNH); 13C NMR (100 MHz, Chloroformꢀd) δ ppm:
148.8, 148.7, 148.6, 141.3, 139.4, 137.3, 135.2, 131.9, 129.9, 129.7,
129.8, 125.5, 124.3, 123.8, 121.5, 121.1, 117.3, 116.7, 116.1, 114.0,
35.1, 31.8; MALDI calculated 1094.6662 (C75H82N8), observed
1095.6741 (M+H)+, 1067.9451 (MꢀN2).
Rf : 0.2 (10% CHCl3 : MeOH); UV Vis. (CHCl3), λabs/nm (log ε):
1
286 (4.81), 427 (5.26), 552 (4.0), 598 (3.89); H NMR (400 MHz,
2-[5-(4-phenyl)-10,15,20-tris(3,5-di-tert-butylphenyl)porphyrinyl]-
Methanolꢀd) δ ppm : 8.70ꢀ8.84 (m, 10H, βH, PyH), 8.6ꢀ8.7 (m, 2H,
PyH), 8.52 (s, 1H triazolyl H), 8.45 (m, 1H, PyH), 8.37 (d, J= 6.8
Hz, 2H, ArH), 8.25 (d, J=4.6 Hz, 1H, PyH), 8.15 (m, 6H, ArH,
1H-1,2,3-triazol-1-yl-pyridine-2,2'-bispyridine
ruthenium(II)
chloride (3)
Porphyrin (2) (0.040 g, 0.0365 mmoles) and cisꢀRu(bpy)2Cl2 (6) PyH), 8.05 (m, 6H, ArH), 7.98 (d, J= 5.36 Hz, 1H, PyH), 7.92 (d, J=
(0.0523 g, 0.108 mmol) were added in a mixture of THF (6 mL) and 5.32 Hz, 1H PyH), 7.88 (m, 2H, PyH), 7.85 (s, 3H, ArH), 7.78 (d, J=
EtOH (6 mL). The solution was then bubbled with N2 for a few 5.36 Hz, 1H, PyH), 7.50ꢀ7.65 (m, 3H PyH), 7.45 (t, J= 6.08 Hz, 2H,
minutes, and heated to 85 °C. After refluxing 15 h, the solvent was PyH), 1.42 (s, 54H, tꢀbutyl); MALDI: calculated 1643.5593
removed under vacuum and the residue was chromatographed on (C95H96Cl2N12RuZn), observed 1543.6770 [(Ru(7)(bpy)2]+Cl.
neutral Al2O3 and the last brown band was collected, using
CHCl3:MeOH (v/v) = 10:1 as eluent (18 % yield ~ 10.47 mg).
1-[5-(1-phenyl)-10,15,20-tris(3,5-di-tert-butyl)phenylporphyrinyl]-
1H-1,2,3-triazole-4-yl pyridine (7)
Rf : 0.3 (10% MeOH : CHCl3); UV Vis. (CHCl3), λabs/nm (log ε):
288 (4.63), 424 (5.42), 520 (4.02), 555 (3.80), 594 (3.51), 650
(3.48); 1H NMR (400 M Hz, Metahnolꢀd) δ ppm : 8.85ꢀ8.76 (m, 8H,
Porphyrin (7ꢀZn) (0.050 g, 0.043 mmoles) in CH2Cl2 (15 mL) was
added HCl in dioxane (20 M, 2.5 mL), stirred at r.t. for 5 min. The
mixture was neutralised with saturated NaHCO3 solution, dried over
sodium sulphate, and the solvent was removed under reduced
pressure to yield the product in 90% yield (0.045g)
βH), 8.69ꢀ8.60 (m, 2H, PyH), 8.52 (s, 1H, triazole H), 8.41ꢀ8.35 (m,
1H, PyH), 8.27 (m, 2H, ArH), 8.22ꢀ8.18 (m, 4H, ArH,PyH), 8.10 (m,
1H, PyH), 8.05 (s, 6H, ArH), 7.96ꢀ7.89 (m, 6H, ArH), 7.65ꢀ7.49 (m,
6H, PyH), 7.23ꢀ7.19 (t, 2H, J= 8 Hz, PyH), 7.11 (d, 2H, J= 8 Hz, Py
H), 1.51 (s, 54 H, tꢀbutyl); MALDI: calculated 1578.6458
(C95H98Cl2N12Ru), observed 1543.6458 [(Ru(2)(bpy)2]+Cl.
Rf : 0.4 (CHCl3); UV Vis. (CHCl3), λabs/nm (log ε): 424(5.57),
520(4.05), 557(3.75), 595(3.60), 651(3.66); 1H NMR (400 MHz,
Chloroformꢀd) δ ppm : 8.88ꢀ8.97 (m, 8H, βH), 8.71 (s, 1H, triazole
H), 8.45 (d, J= 8.4 Hz, 2H, PyH), 8.39 (d, 2H, ArH), 8.24 (d, J= 8.4
Hz, 1H, PyH), 8.10 (m, 7H, ArH, PyH), 7.90 (t, J= 7.64 Hz, 1H,
PyH,), 7.81 (s, 3H, ArH), 7.34 (t, 1H, PyH), 1.51 (s, 54H, tꢀbutyl), ꢀ
2-[5-(1-phenyl)-10,15,20-tris(3,5-di-tert-butylphenyl)porphyrinato
zinc]-1H-1,2,3-triazol-4-yl)pyridine (7ꢀZn)
Zinc acetate (0.18 g, 0.83 mmoles) was dissolved in 1:1 2.70 (br.s., 2H, ꢀNH); 13C NMR (100 MHz, Chloroformꢀd) δ ppm:
MeOH/CHCl3 (50 mL) and added to porphyrin 6. The reaction was 149.6, 148.8, 148.7, 143.5, 141.2, 137.3, 135.6, 131.9, 129.9, 129.8,
refluxed for 1 h and the crude mixture was washed three times with 123.4, 121.7, 121.1, 120.7, 120.3, 118.7, 31.8, 35.1; ESI MS:
water. The organic layer was dried over Na2SO4 and filtered. 2ꢀ calculated 1094.662 (C75H82N8), observed 1095.6715 (M+H)+,
ethynyl pyridine (75.83 ꢂL, 365.31 mmoles) was added to a mixture 548.3394 (M+2H)2+.
of Zn porphyrin (0.200 g, 0.195 mmoles), CuSO4.5H2O (7.25 mg,
349.85 mmoles), sodium ascorbate (11.6 mg, 278.06 mmoles),
1-[5-(1-phenyl)-10,15,20-tris(3,5-di-tert-butyl)phenylporphyrinyl]-
DIPEA (75.83 ꢂL, 181.76 mmoles) in DCM/H2O/EtOH (5:2:1) (60
mL) and stirred at 50 ℃ for 12 h. After cooling, the reaction mixture
was diluted with CH2Cl2 (20 mL) and washed with water. The
resulting organic layer was dried over Na2SO4 and evaporated to
dryness. The residue was purified by silica gel coloumn
chromatography using 7:3 CHCl3/petroleum ether as eluent to yield
the desired product in 85% yield (0.198 g).
1H-1,2,3-triazol-4-yl-pyridine-2,2'-bispyridine
ruthenium(II)
chloride (8)
Porphyrin (7) (0.040 g, 0.0365 mmoles) and cisꢀRu(bpy)2Cl2 (6)
(0.0523 g, 0.108 mmol) were added in a mixture of THF (6 mL) and
EtOH (6 mL). The solution was then bubbled with N2 for a few
minutes, and heated to 85 °C. After refluxing 15 h, the solvent was
removed under vacuum and the residue was chromatographed on
neutral Al2O3 and the last brown band was collected, using
CHCl3:MeOH (v/v) = 10:1 as eluent (18 % yield ~ 10 mg).
Rf : 0.3 (CHCl3); UV−visible (CHCl3) λabs/nm (log ε): 427 (5.65),
1
556 (4.32), 598 (4.02); H NMR (400 MHz, Chloroformꢀd) δ ppm:
8.93ꢀ9.04 (m, 8H, βH), 8.70 (s, 1H, triazole H), 8.45 (m, 1H, Py H),
8.40 (d, J= 7.48 Hz, 2H, ArH), 8.25 (d, J= 9.56 Hz, 1H, PyH), 8.15
(d, J= 7.48 Hz, 2H, ArH), 8.05 (s, 6H, ArH), 7.85 (t, J= 8.56 Hz, 1H,
PyH), 7.81 (s, 3H, ArH), 7.10 (dd, J= 7.48 Hz, 1H, PyH), 1.51 (s,
54H, tꢀbutyl); 13C NMR (100 MHz, Chloroformꢀd) δ ppm: 150.5,
150.4, 150.3, 149.6, 149.1, 148.5, 141.8, 139.2, 137.0, 136.1, 135.4,
132.5, 132.3, 132.2, 131.1, 129.7, 129.6, 122.6, 120.7, 120.5, 119.9,
Rf : 0.3 (10% MeOH : CHCl3); UV Vis. (CHCl3), λabs/nm (log ε):
295(4.71), 425(5.57), 521(4.05), 556(3.57), 596(3.60), 651(3.66); 1H
NMR (400 M Hz, Methanolꢀd) δ ppm : 8.83ꢀ8.65 (m, 10H, βH,
PyH), 8.62ꢀ8.52 (m, 3H, PyH, triazolyl H), 8.48 (d, 1H, PyH), 8.37
(d, 2H, ArH), 8.25 (d, 1H, PyH), 8.2ꢀ8.1 (m, 6H, ArH,PyH), 8.05 (s,
6H, ArH), 7.96 (d, 1H, PyH), 7.93ꢀ7.84 (m, 3H, PyH), 7.78 (d, 1H,
PyH), 7.64ꢀ7.5 (m, 5H, Py H), 7.48ꢀ7.42 (m, 2H, Py H) , 1.51 (s, 54
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 8 of 9
View Article Online
DOI: 10.1039/C6NJ01676F
ARTICLE
Journal Name
H, tꢀbutyl); MALDI: calculated 1578.6458 (C95H98Cl2N12Ru), 18. Chauhan, S.M.S.; Kumar, A.; Srinivas, K.A.; Mishra, M.K.
observed 1480.7020 [(Ru(7ꢀN2)(bpy)2]+.
Indian Journal of Biochem and Biophys, 2003, 40, 429ꢀ438.
19. Lee, J.; Kim, Y.; Kang, S. K.; Choi, I.; Yi, J. Korean J. Chem.
Eng., 2006, 23(3), 512ꢀ515.
20. Bryden F.; Boyle, R. W. Synlett., 2013, 24, 1978–1982.
21. a) Hohloch, S.; Schweinfurth, D.; Sommer, M. G.; Weisser, F.;
Deibel, N.; Ehret, F.; Sarkar, B. Dalton Trans., 2014, 43, 4437ꢀ
4450; b) Richardson, C.; Fitchett, C. M.; Keene, F. R.; Steel, P.,
Dalton Trans., 2008, 2534ꢀ2537.
22. Merckx, T.; Haynes, C. J. E.; Karagiannidis, L. E.; Clarke, H. J.;
Holder, K.; Kelly, A.; Tizzard, G. J.; Coles, S. J.; Verwilst, P.;
Gale, P. A.; Dehaen, W. Org. Biomol. Chem., 2015, 13, 1654ꢀ
1661.
Acknowledgements
We are grateful to acknowledge the Council of Scientific and
Industrial Research (CSIR), New Delhi, University Grants
Commissions (UGC), New Delhi, for financial assistance and USIC,
University of Delhi, and Prof. R. Nagarajan, Prof. Pawan Mathur for
cyclic voltammetry measurements.
References
23. Ryan, A.; Gehrold, A.; Perusitti, R.; Pintea, M.; Fazekas, M.;
Locos, O. B.; Blaikie, F.; Senge, M. O. Eur. J. Org. Chem., 2011,
5817ꢀ5844.
24. Toma, H. E.; Araki, K. Coord. Chem. Rev., 2000, 196, 307ꢀ329.
25. LeGourriérec, D.; Andersson, M.; Davidsson, J.; Mukhtar, E.;
Sun, L.; Hammarström, L. J. Phys. Chem. A, 1999, 103, 557ꢀ559.
26. Lo, W. K. C.; Huff, G. S.; Cubanski, J. R.; Kennedy, A. D.
W.; McAdam, C. J.; McMorran, D. A.; Gordon, K. C.; Crowley, J.
D. Inorg. Chem., 2015, 54, 1572ꢀ1587.
27. Liu, X.; Liu, J.; Jin, K.; Yang, X.; Peng, Q.; Sun, L.
Tetrahedron, 2005, 61, 5655–5662.
28. Bobby, H.; Escudero, D.; Hager, M. D.; Friebe, C.; Winter,
A.; Gorls, H.; Altuntas, E.; Gonzalez, L.; Schubert, U. S. J.
Org. Chem., 2010, 75, 4025ꢀ4038.
1. Komatsu, T.; Moritake, M.; Tsuchida, E. Chem. Eur. J., 2003, 9,
4626ꢀ4633.
2. a) Kalyanasundaram, K. Photochemistry of polypyridines and
porphyrin complexes. London: Academic Press; 1992; b) Panda,
M. K.; Ladomenou, K.; Coutsolelos, A.G. Coord. Chem. Rev.,
2012, 256, 2601–2627.
3. Imahori, H. Bull. Chem. Soc. Jpn. 2007, 80, 621.
4. Sauvage, J. P.; Collin, J. P.; Chambron, J. C.; Guillerez, S.;
Coudret, C.; Chem. Rev., 1994, 94, 993ꢀ1019.
5. Togashi, T.; Izumi, A.; Kon, H.; Kanaizuka, K.; Ishizaki, M.;
Miyake, R.; Chang, H. C.; Haga, M.; Sakamoto, M.; Kurihara M.
Chem. Lett., 2014, 43, 1201–1203.
6. LeGourriérec, D.; Andersson, M.; Davidsson, J.; Mukhtar, E.;
Sun, L.; Hammarström, L. J. Phys. Chem. A, 1999, 103, 557ꢀ559.
7. Liu, X.; Liu, J.; Pan, J.; Anderssonb, S.; Sun, L. Tetrahedron,
2007, 63, 9195ꢀ9205 and references therein.
8. a) Schulze, B.; Schubert, U. S. Chem. Soc. Rev., 2014, 43, 2522;
b) Struthers, H.; Mindt, T. L.; Schibli, R. Dalton Trans., 2010, 39,
675–696; c) Crowley, J. D.; McMorran, D. A. Top. Heterocycl.
Chem., 28, 31ꢀ83; d) Elliott, P. I. P. in Organomet. Chem., 2014,
39, Ch 1, 1ꢀ25.
9. a) Fazio, M. A.; Lee, O. P.; Schuster, D. I. Org Lett., 2008, 21,
4979ꢀ4982; b) Miguel, G. D.; Wielopolski, M.; Schuster, D. I.;
Fazio, M. A.; Lee, O. P.; Haley, C. K.; Ortiz, A. L.; Echegoyen,
L.; Clark, T.; Guldi, D. M. J. Am. Chem. Soc., 2011, 133, 13036ꢀ
13054; c) Schuster, D. I.; Li, K.; Guldi, D. M.; Palkar, A.;
Echegoyen, L.; Stanisky, C.; Cross, R. J.; Niemi, M.; Tkachenko,
N. V.; Lemmetyinen, H. J. Am. Chem. Soc., 2007, 129, 15973ꢀ
15982; d) Natali, M.; Ravaglia, M.; Scandola, F.; Boixel, J.;
Pellegrin, Y.; Blart, E.; Odobel, F., J. Phys. Chem. C, 2013, 117,
19334−19345.
10. Wang, H. X.; Zhou, K. G.; Xie, Y. L.; Zeng, J.; Chai, N. N.; Li,
J.; Zhang, H. L. Chem. Commun., 2011, 47, 5747–5749.
11. a) Punidha, S.; Sinha, J.; Kumar, A.; Ravikanth, M. J. Org.
Chem., 2008, 73, 323ꢀ326; b) Shetti, V. S.; Ravikanth, M. Eur. J.
Org. Chem., 2010, 494–508.
12. Li, H.; Cheng, F.; Duft, A. M.; Adronov, A. J. Am. Chem. Soc.,
2005, 127, 14518.
13. Stengel, I.; Mishra, A.; Pootrakulchote, N.; Moon, S. J.;
Zakeeruddin, S. M.; Grätzel, M.; Bäuerle, P. J. Mater. Chem.,
2011, 21, 3726.
14. Stengel, I.; Mishra, A.; Pootrakulchote, N.; Moon, S. J.;
Zakeeruddin, S. M.; Grätzel, M.; Bäuerle, P. J. Mater. Chem.,
2011, 21, 3726ꢀ3734.
15. Kolb, H.C.; Sharpless, K. B. Drug Discovery Today, 2003, 8,
1128ꢀ1137.
16. Lee, C. W.; Lu, H. P.; Lan, C. M.; Huang, Y. L.; Liang, Y. R.;
Yen W. N.; Liu, Y. C.; Lin, Y. S.; Diau, E. W. G.; Yeh, C. Y.
Chem. Eur. J., 2009, 15, 1403ꢀ1412.
17. Fletcher, J. T.; Bumgarner, B. J.; Engels, N. D.; Skoglund, D. A.
Organometallics, 2008, 27, 5430ꢀ5433.
8 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 9 of 9
New Journal of Chemistry
View Article Online
DOI: 10.1039/C6NJ01676F
A family of inverse and regular triazolyl-pyridyl porphyrin-ruthenium(II) conjugates display an energy
transfer from porphyrin to ruthenium bipyridyl moiety and a narrower HOMO/LUMO energy band gap
which would help in increasing the electronic coupling, thus enhancing charge transfer in conjugates.