Inorganic Chemistry
Article
M solution) while the reaction mixture was stirred at room
temperature for 1 h under a nitrogen atmosphere. 2,3-Dichloro-5,6-
dicyanobenzoquinone (DDQ; 0.33 g, 1.53 mmol) was then added, and
the reaction mixture was stirred in air for an additional 1 h. The
solvent was removed under reduced pressure, and the crude
compound was purified by silica gel column chromatography using
petroleum ether/dichloromethane (60:40) to afford porphyrin 6.
EXPERIMENTAL SECTION
■
Chemicals. All general chemicals and solvents were procured from
SD Fine Chemicals, India. Column chromatography was performed
using silica gel and basic alumina obtained from Sisco Research
Laboratories, India. All of the solvents used were of analytical grade
and were purified and dried by routine procedures immediately before
use.
1
Yield: 20%. Mp: >300 °C. H NMR (400 MHz, CDCl3): δ 2.70 (s,
1
Instrumentation. H NMR spectra were recorded with a Bruker
6H, CH3), 4.10 (s, 6H, OCH3), 7.32 (d, J = 8.7 Hz, 4H, Ar), 7.61 (d, J
= 7.8 Hz, 4H, Ar), 8.09 (d, J = 8.2 Hz, 4H, Ar), 8.12 (d, J = 7.8 Hz,
4H, Ar), 8.68 (s, 4H, β-pyrrole), 9.68 (s, 4H, β-thiophene). HRMS
(ES+). Calcd for C48H36N2O2S2: m/z 736.9416 ([M]+). Found: m/z
737.2287 ([M + H]+).
400 MHz instrument using tetramethylsilane as an internal standard.
1H−1H COSY, NOESY, and DOSY NMR experiments were
performed on a Bruker 400 MHz instrument. All NMR measurements
were carried out at room temperature in deuterated chloroform
(CDCl3). Absorption and steady-state fluorescence spectra were
recorded on PerkinElmer Lambda-35 and Varian Cary-Eclipse
instruments, respectively. The concentrations used for the absorption
study were 1 × 10−6 and 1 × 10−5 M for the Soret and Q bands,
respectively. The concentration used for the steady-state fluorescence
study was 1 × 10−6 M. The fluorescence quantum yields (Φf) were
estimated from the emission and absorption spectra by a comparative
method. The time-resolved fluorescence decay measurements were
carried out at magic angle using a picosecond diode-laser-based time-
correlated single-photon-counting (TCSPC) fluorescence spectrom-
eter from IBH, Swindon, U.K. MALDI-TOF MS spectra were
recorded from a MALDI-TOF Spec-2E instrument manufactured by
Micromass, Wilmslow, U.K. Cyclic and differential-pulse voltammetric
studies were carried out on a BAS electrochemical system utilizing the
three-electrode configuration consisting of glassy carbon (working),
platinum wire (auxiliary), and saturated calomel (reference) electrodes
in dry dichloromethane using 0.1 M TBAP as the supporting
electrolyte.
5,10-Bis(p-hydroxyphenyl)-15,20-bis(p-tolyl)-21,23-dithia-
porphyrin (4). Compound 4 was synthesized by refluxing porphyrin
6 (0.1 g, 14 mmol) in 30 mL of hydrogen bromide/water (49%) for 4
h. The reaction mixture was extracted with dichloromethane and
washed several times with water and a dilute ammonia solution (25%,
v/v). The organic layer was evaporated under reduced pressure and
subjected to silica gel column chromatographic purification using
dichloromethane to afford pure 9. Yield: 68%. Mp: >300 °C. 1H NMR
(400 MHz, CDCl3): δ 2.70 (s, 6H, CH3), 7.20 (d, J = 9.0 Hz, 4H, Ar),
7.61 (d, J = 7.8 Hz, 4H, Ar), 8.10 (d, J = 8.2 Hz, 4H, Ar), 8.19 (d, J =
7.8 Hz, 4H, Ar), 8.70 (s, 4H, β-pyrrole), 9.71 (s, 4H, β-thiophene).
HRMS (ES+). calcd for C46H32N2O2S2 ([M]+): m/z 708.8885. Found:
m/z 709.2002 ([M + H]+).
General Synthesis of Tetrads 1 and 2. Tetrads 1 and 2 were
synthesized by refluxing 1 equiv of 9 with 1 equiv of 3 and 4,
respectively, in dry benzene for 12 h under a nitrogen atmosphere.
The solvent was evaporated under reduced pressure, and the resulting
residue was subjected to an alumina column. The desired product was
eluted with petroleum ether/dicholoromethane (30:70) to afford
tetrads 1 and 2 in 65−70% yield.
Single crystals of suitable size for the X-ray diffractometer were
selected under a microscope and mounted on the tip of a glass fiber,
which was positioned on a copper pin. The X-ray data for tetrad 2
(CCDC 1564602) were collected on a Bruker Kappa CCD
diffractometer, employing graphite-monochromated Mo Kα radiation
at 200 K and the θ−2θ scan mode. The space group for tetrad 2 was
determined on the basis of systematic absences and intensity statistics,
and the structure of tetrad 2 was solved by direct methods using SIR92
or SIR97 and refined with SHELXL-97.64
Dihydroxy[5,10,15,20-tetrakis(p-tolyl)porphyrinato]tin(IV)
[9; SnIVTTP(OH)2]. Compound 9 was synthesized by treating H2TTP
(3 mmol) in CHCl3 with 10 equiv of SnCl2·2H2O. The progress of the
reaction was monitored by TLC and absorption spectroscopy. After
the formation of a new spot on the TLC spectrum and the
disappearance of the starting materials, the reaction was stopped and
subjected to basic alumina column chromatography. The required
compound 9 was collected in 90% yield as a purple solid.49 Mp: >300
°C. 1H NMR (400 MHz, CDCl3): δ −7.43 (s, 2H, br, axial OH), 2.70
(s, 12H, CH3), 7.61 (d, J = 7.8 Hz, 8H, Ar), 8.20 (d, J = 7.8 Hz, 8H,
Ar), 9.13 (s, satellite, J = 10.7 Hz, 8H, β-pyrrole).
1
Tetrad 1. Yield: 65%. H NMR (400 MHz, CDCl3): δ −2.88 (s,
2H, inner NH), 2.16 (s, 12H, CH3 type I), 2.46 (d, J = 8.24 Hz, 8H,
phenoxo type α), 2.57 (s, 12H, CH3 type II), 2.82 (s, 12H, CH3 type
III), 6.70 (d, J = 8.24 Hz, 8H, phenoxo type β), 6.83 (d, J = 7.64 Hz,
8H, Ar, type m′), 7.44 (d, J = 7.88 Hz, 8H, Ar, type m″), 7.58 (d, J =
4.68 Hz, 4H, β-pyrrole N3S unit, type f), 7.77 (d, J = 7.92 Hz, 8H, Ar,
type m), 7.90 (d, J = 7.88 Hz, 8H, Ar, type o″), 8.19 (d, J = 4.60 Hz,
4H, β-pyrrole N3S unit, type g), 8.20 (d, J = 7.76 Hz, 8H, Ar, type o′),
8.51 (d, J = 7.88 Hz, 8H, Ar, type o), 8.88 (s, 4H, β-pyrrole N3S unit,
type e), 9.31 (d, J = 4.60 Hz, 4H, β-pyrrole SnP, type a), 9.48 (d, J =
4.60 Hz, 4H, β-pyrrole SnP, type b), 9.51 (s, 4H, β-pyrrole SnP, type
d), 9.55 (s, 4H, β-thiophene N3S), 9.88 (s, 4H, β-pyrrole SnP, type c).
MALDI-TOF MS. Calcd: m/z 2954.7 ([M]+). Found: m/z 2956.7
(M+ + 2).
1
Tetrad 2. Yield: 70%. H NMR (400 MHz, CDCl3): δ 2.06 (s,
12H, CH3 type I), 2.52 (d, J = 7.2 Hz 8H, phenoxo type α), 2.59 (s,
12H, CH3 type II), 2.83 (s, 12H, CH3 type III), 6.77 (d, J = 7.2 Hz,
8H, phenoxo type β), 6.78 (d, J = 7.4 Hz, 8H, Ar, type m′), 7.46 (d, J =
7.9 Hz, 8H, Ar, type m″), 7.54 (d, J = 4.7 Hz, 4H, β-pyrrole N3S unit,
type f), 7.78 (d, J = 8.0 Hz, 8H, Ar, type m), 7.92 (d, J = 7.9 Hz, 8H,
Ar, type o″), 8.16 (d, J = 7.9 Hz, 8H, Ar, type o′), 8.23 (d, J = 4.6 Hz,
4H, β-pyrrole N3S unit, type g), 8.51 (d, J = 8.0 Hz, 8H, Ar, type o),
9.27 (d, J = 4.6 Hz, 4H, β-pyrrole SnP, type a), 9.47 (d, J = 4.6 Hz, 4H,
β-pyrrole SnP, type b), 9.51 (s, 4H, β-pyrrole SnP, type d), 9.53 (s,
4H, β-thiophene N3S), 9.62 (s,4H, β-thiophene N3S), 9.89 (s, β-
pyrrole SnP, type c). MALDI-TOF MS. Calcd: ([M]+): m/z 2988.8.
Found: m/z 2990.6 (M+ + 2).
DFT Calculations of Monomers 3, 4, and 9 and Tetrads 1
and 2. The geometry optimizations were performed using the Vienna
ab initio software package (VASP).65 The PBE functional66 and the
projected-augmented-wave67 potential method embedded in the VASP
code were used to describe the core−valence electron interactions.
Long-range dispersion interactions were described using the DFT-D2
method of Stefan Grimme.68 The initial positions for monomers 3, 4,
and 9 were constructed and relaxed in the Avogadro software
package.69 Tetrads 1 and 2 were constructed from their respective
monomers and subjected to simulated annealing. Subsequently, the
5,10-Bis(p-hydroxyphenyl)-15,20-bis(p-tolyl)-21-dithiapor-
phyrin (3). The required porphyrin 3 was synthesized by condensing
2,5-bis(p-tolylhydroxyl)methylthiophene (5; 12.29 mmol, 1.25 mL)
and p-hydroxybenzaldehyde (4.09 mmol, 500 mg) with pyrrole (16.39
mmol, 1.11 mL) in propionic acid at 70 °C for about 4 h. The crude
compound was showing about six spots on the TLC spectrum, which
was purified by silica gel column chromatography using a CH2Cl2/
petroleum ether mixture (2:3) as the eluent to afford 3 in 10% yield.
1
Mp: >300 °C. H NMR (400 MHz, CDCl3): δ −2.69 (s, 1H, NH),
2.70 (s, 6H, CH3), 7.18 (d, J = 7.9 Hz, 4H, Ar), 7.61 (d, J = 7.9 Hz,
4H, Ar), 8.10 (d, J = 8.2 Hz, 4H, Ar), 8.18 (d, J = 8.2 Hz, 4H, Ar), 8.60
(d, J = 4.60 Hz, β-pyrrole), 8.70 (d, J = 4.60 Hz, β-pyrrole), 8.90 (s,
2H, β-pyrrole), 9.75 (s, 2H, β-thiophene). ES-MS. Calcd for
C46H33N3O2S ([M]+): m/z 691.8. Obsd: m/z 691.5.
5,10-Bis(p-methoxyphenyl)-15,20-bis(p-tolyl)-21,23-dithia-
porphyrin (6). The samples of 2,5-bis(p-anisyl)-
hydroxymethylthiophene (8; 0.5 g, 1.53 mmol) and 16-thiatripyrrane
(0.65 g, 1.53 mmol) were dissolved in dichloromethane (300 mL), and
the reaction flask was degassed with nitrogen for 10 min with stirring.
The condensation was initiated by adding BF3·OEt2 (0.4 mL of a 2.5
N
Inorg. Chem. XXXX, XXX, XXX−XXX