Stepwise synthesis and spectral characteristics of meso-trans-diphenyldi(1- naphthyl)tetrabenzoporphin and its zinc complex

Article abstract of DOI:10.1023/B:RUJO.0000010191.89008.ee

A reaction of phthalimide with phenylacetic acid in the presence of zinc oxide furnished 3-oxoisoindolenyl-3′-oxoisoindolinylidene-1,1′- benzylidine which at heating with 1-naphthylacetic acid in the presence of zinc oxide provided zinc meso-trans-diphenyldi(1-naphthyl)tetrabenzoporphin complex. Proceeding from this compound a meso-trans-diphenyldi(1-naphthyl) tetrabenzoporphin was prepared. The spectral characteristics of compounds obtained were studied.

Full text of DOI:10.1023/B:RUJO.0000010191.89008.ee

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Russian Journal of Organic Chemistry, Vol. 39, No. 8, 2003, pp. 1183 1187. Translated from Zhurnal Organicheskoi Khimii, Vol. 39, No. 8, 2003,
pp. 1254 1258.
Original Russian Text Copyright 2003 by Galanin, Kudrik, Shaposhnikov.
Stepwise Synthesis and Spectral Characteristics
of meso-trans-Diphenyldi(1-naphthyl)tetrabenzoporphin
and Its Zinc Complex
N. E. Galanin, E. V. Kudrik, and G. P. Shaposhnikov
Ivanovo State Chemico-technological University, Ivanovo, 153460 Russia
Received October 2, 2002
Abstract A reaction of phthalimide with phenylacetic acid in the presence of zinc oxide furnished
3-oxoisoindolenyl-3 -oxoisoindolinylidene-1,1 -benzylidine which at heating with 1-naphthylacetic acid in
the presence of zinc oxide provided zinc meso-trans-diphenyldi(1-naphthyl)tetrabenzoporphin complex.
Proceeding from this compound a meso-trans-diphenyldi(1-naphthyl)tetrabenzoporphin was prepared.
The spectral characteristics of compounds obtained were studied.
meso-Substituted tetrabenzoporphins and their metal
complexes posess versatile valuable practical pro-
perties. For instance, some of this group compounds
were suggested as fat-soluble dyes [1], photochrome
filters [2], photosensitizers for generation of singlet
oxygen in photodynamic therapy of cancer [3].
complex could be performed using the product of
phthalimide condensation with acetic or malonic acids
in the presence of metal acetates, 3-oxoisoindolenyl-
3 oxoisoindolin-lidyne-1,1 -methylidine (III).
The symmetrically substituted meso-tetraaryltetra-
benzoporphins are now studied in sufficient detail
[4 6] in contrast to unsymmetrically substituted ones.
Therewith the published information concerns only
the products of incomplete meso-substitution in the
tetrabenzoporphin [7 9]. We did not find any publish-
ed data on the synthesis and characteristics of
unsymmetrically
substituted
meso-tetraaryltetra-
benzoporphins containing different aryl moieties in
the meso-positions. However such compounds may
be of practical use. The analysis of published data on
the synthesis of meso-aryltetrabenzoporphins suggests
that compounds of unsymmetrical structure are
available only by stepwise condensation since the
simultaneous heating of two arylacetic acids with
phthalimide can afford a mixture of six possible tetra-
benzoporphins which would provide great difficulties
at preparative separation of the components.
By the reaction between phthalimine and phenyl-
acetic acid in the presence of zinc oxide at 230 C
within 30 min we obtained a phenyl-substituted
analog of compound III, 3-oxoisoindolenyl-3 -oxo-
isoindolinylidene-1,1 -benzylidine (IV).
Dimer IV formed through an intermediate stage of
3-benzylidenephthalimidine (V) along Scheme 1.
On completion of reaction the reaction mixture
was cooled, treated with a solution of hydrochloric
acid, and washed with hot water. Compound IV was
isolated by column chromatography on alumina;
besides the main product were isolated small amounts
of 3-benzylidenephthalimidine (V), a light-yellow
crystalline compound, and of meso-tetraphenyltetra-
benzoporphin.
On the basis of the above the target of this study
was investigation of reaction products of phenylacetic
acid and phthalimide, intermediates in the synthesis
of meso-tetraphenyltetrabenzoporphin, and a develop-
ment of a procedure for preparation of meso-trans-
diphenyldi(1-naphthyl)tetrabenzoporphin (I) and its
complex with zinc II.
3-Oxoisoindolenyl-3 -oxoisoindolinylidene-1,1 -
benzylidine (IV) is a red crystalline compound well
soluble in polar and nonpolar organic solvents. Its
It was formerly shown [8] that a selective synthesis
of
zinc
meso-trans-diphenyltetrabenzoporphin
1070-4280/03/3908-1183$25.00 2003 MAIK Nauka/Interperiodica

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1184
GALANIN et al.
Scheme 1.
In the IR spectrum of compound IV appear ab-
sorption bands at 1766 and 1726 cm evidencing the
1
presence of C=O groups. The bands at 1363 and
1288 cm 1 belong to the stretching vibrations of the
1
C=N bonds, that at 3181 cm to the stretching vibr-
ations of the N-H bond. It is important that the band
of the stretching vibrations of the N-H bond is con-
siderably shifted to high frequency region and appears
in the same place as the analogous absorption in
metal-free porphyrins. This result together with the
1H NMR data permits a conclusion that dimer IV
exists as a cis-isomer stabilized by formation of an
intramolecular hydrogen bond N H...N.
1
Thus in the H NMR spectrum of compound IV
the most downfield peak is the resonance of the
proton from imide ring (a broadened singlet at
8.69 ppm). In the region 7.81 7.62 ppm appears a
multiplet corresponding to three o- and p-protons of
the phenyl substituent. The signals of two m-protons
of the phenyl substituent are observed as a triplet at
7.59 7.52 ppm The resonance of 8 protons from the
isoindole fragments appears as a multiplet in the
region 7.50 7.13 ppm.
structure was confirmed by elemental analysis and
In the spectrum of 3-benzylidenephthalimidine (V)
the proton signal of the imide ring is observed as a
singlet at 10.6 ppm. The upfield shift of the similar
signal in the spectrum of compound IV and its
broadening is due to the already mentioned possibility
of formation of an intramolecular hydrogen bond with
the nitrogen atom of the second isoindole fragment.
To confirm this assumption we carried out quantum-
chemical calculations of molecule IV by the semi-
empirical AM1 method. The calculation results show
that the distance from the hydrogen atom of the imide
1
electronic, vibration, and H and 13C NMR spectra.
In the electron absorption spectrum of compound
IV in the visible region three absorption bands at 523,
489, 458 nm are present. The comparison of this
spectrum with that of compound III [8] shows that
introduction into the molecule of III of a phenyl sub-
stituent resulted in a blue shift of the absorption bands
by 25 nm apparently because the planar structure of
molecule IV is disrupted due to the steric effect of the
phenyl substituent.
ring and the nitrogen of the imidine moiety is 2.44
and thus the hydrogen bond formation is probable.
,
In the 13C NMR spectrum of compound IV the
most upfield signal at 106.46 ppm corresponds to the
carbon linked to the carbonyl in the imide ring; the
signal of the similar carbon from the imidine ring
appears at 112.30 ppm. The carbon signals from
atoms in the imide and imidine rings bonded to the
benzylidene fragment are observed in the region
120.16 and 123.88 ppm respectively. The other
carbon signals are seen in the region 128.13
138.99 ppm, and their assignment is difficult.
The zinc complex of meso-trans-diphenyldi(1-
naphthyl)tetrabenzoporphin (II) was obtained by heat-
ing 3-oxoisoindolenyl-3 -oxoisoindolinylidene-1,1 -
benzilidine (IV) with 1-naphthylacetic acid (VI) in the
presence of zinc oxide at 340 C for 30 min according
to the following Scheme 2.
Fig. 1. Electron absorption spectrum of 3-oxoisoindolenyl-
3 -oxoisoindolinylidene-1,1 -benzylidine(IV) in chloro-
form.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 8 2003

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STEPWISE SYNTHESIS AND SPECTRAL CHARACTERISTICS
Scheme 2.
1185
The target metal complex II was isolated from the
reaction mixture by column chromatography on
tetrabenzoporphin [4]. For instance, the longwave
component of the Q-band in the spectrum of por-
aluminum oxide. As eluent was used a mixture chloro- phyrin I (Fig. 3) has the same intensity as the short-
form-hexane, 1: 5.
wave component whereas in the spectrum of the
The synthesis of metal-free meso-trans-diphenyldi-
(1-naphthyl)tetrabenzoporphin (I) was performed by
treating the zinc colmplex II with concn. Hydro-
chloric acid in chloroform. Then the reaction mixture
was washed with ammonia solution and water till
pH 7. The organic layer was separated, the solvent
was evaporated, and the residue was subjected to
chromatography on a column charged with silica gel
using as eluent a mixture dichloromethane-ethanol,
100: 1 by volume. Porphyrins I and II are dark-green
substances, well soluble in various organic solvents.
Their homogeneity was confirmed by TLC, the struc-
ture was proved by elemental analysis, by electronic
and vibration spectroscopy, and by mass spectrometry.
Fig. 2. Electron absorption spectrum of zinc meso-trans-
The electron absorption spectrum of compound II
(Fig. 2) has the pattern characteristic of tetrabenzo-
porphins metal cpmplexes: In the visible region the
spectrum contains two main absorption bands, a
strong Soret band with a maximum at 463 nm and a
less strong Q-band in the longwave region with a
maximum at 654 nm. The comparison of the spec-
trum of compound II with that of zinc meso-tetra-
phenyltetrabenzoporphin [4] shows that replacement
of two phenyl moieties by naphthyl ones results in
a red shift of the maxima of the main absorption band
by 35 nm.
diphenyldi(1-naphthyl)tetrabenzoporphin in chloroform.
This shift may be attributed to higher positive
inductive effect of the meso-naphthyl substituents
compared to phenyls.
As to the spectrum of metal-free porphyrin I
(Fig. 3), therein significant changes are observed in
the intensity ratio of the main absorption bands as
compared to the spectrum of the meso-tetraphenyl-
Fig. 3. Electron absorption spectrum of meso-trans-di-
phenyldi(1-naphthyl)tetrabenzoporphin in dichloromethane.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 8 2003

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1186
GALANIN et al.
ed on spectrometer Bruker AMD-300X. BBA-mass
spectra (in m-nitrobenzyl alcohol matrix) were
measured on JEOL JMS 700 instrument.
3-Oxoisoindolenyl-3 -oxoisoindolinylidene-1,1 -
benzylidine (IV). A mixture of 6 g of phthalimide,
2.5 g of phenylacetic acid, and 1.6 g of zinc oxide
was heated in a test tube for 30 min at 240 C, then
the melt was cooled, crushed, and boiled in a beaker
with 100 ml of 10% hydrochloric acid for 5 min.
Then the mixture was filtered, and the precipitate was
washed on the filter with 200 ml of hot water. After
drying the product was dissolved in chloroform and
subjected to chromatography on a column charged
with aluminum oxide of the II grade of activity
(eluent chloroform). The main (second) bright-red
zone was collected, the solvent was removed, and we
obtained 1.6 g (24.9%) of compound IV as a dark-red
powder. Electron absorption spectrum, max, nm (D)
(chloroform): 523 (0.134), 489 (0.158), 458 (0.156).
1H NMR spectrum (CD2Cl2), , ppm: 8.69 s (1H),
7.81 7.62 m (3H), 7.59 7.52 t (2H), 7.50 7.13 m
(8H). 13C NMR spectrum (CD2Cl2), , ppm: 138.99,
136.15, 135.68, 135.60, 134.73, 133.63, 130.71,
129.86, 129.67, 128.13, 123.88, 120.16, 112.30,
106.46. IR spectrum, cm 1 (KBr pellets): 3181(N H),
2920 (C-H), 1766, 1726 (C=O), 1363, 1288 (C=N),
778, 616, 582. Well soluble in DMF, chloroform,
benzene, acetone, insoluble in water, diluted acids
and alkalis. Found, %: C 79.25; H 4.10; N 7.85.
C23H14N2O2. Calculated, %: C 78.84; H 4.03;
N 8.00.
Fig. 4. Geometric structure of meso-trans-diphenyldi(1-
naphtyl)tetrabenzoporphin (I) molecule according to
AM-1calculations.
meso-tetraphenyltetrabenzoporphin the intensity of the
latter is notably smaller.
Besides in the spectrum of compound I as compar-
ed to the spectrum of meso-tetraphenyltetrabenzo-
porphin a significant blue shift (up to 18 nm) is ob-
served of the main absorption bands. We believe that
the cause of the above shift lies in the additional
asymmetry and in the increased size of substituents
in going from meso- phenyl to meso-naphtyl substitu-
ents that in the absence of the stabilizing effect of the
metal complexing results in notable distortion of the
porphyrin molecule accompanied with somewhat
decreased macroring aromaticity.
Quantum-chemical calculations of meso-trans-di-
phenyldi(1-naphthyl)tetrabenzoporphin (I) molecule
by AM-1 method support the above assumption. The
results of calculations are presented on Fig. 4 as a
PLUTO-model. As seen, the molecule of compound
I is actually strongly distorted, and the latter fact
governs its spectral characteristics. It should be also
noted that in the electronic spectrum of porphyrin I
on the spectral curve in the region 347 nm appears a
shoulder characteristic of the absorption in the
naphthalene moieties.
From the first light-yellow zone on removing the
solvent we isolated 0.07 g of 3-benzylidenephthal-
imidine (V). 1H NMR spectrum (CD2Cl2), d, ppm:
10.52 s (1H), 7.95 d (1H), 7.75 d (1H), 7.70 7.55 m
(2H), 7.45 7.40 t (1H), 7.40 7.30 t (2H), 7.20
7.10 m (2H), 6.55 s (1H). A light-yellow powder ,
well soluble in DMF, chloroform, benzene, acetone,
insoluble in water, diluted acids and alkalis. Found,
%: C 81.80; H 5.70; N 6.25. C15H11NO. Calculat-
ed, %: C 81.43; H 5.01; N 6.33.
Thus we succeeded in the synthesis of meso-aryl
substituted tetrabenzoporphins of unsymmetrical
structure. The analysis of spectral data and quantum-
chemical calculations permitted an assumption on
nonplanar structure of porphyrins syntheized.
Zinc complex of meso-trans-diphenyldi-
(1-naphthyl)tetrabenzoporphin (II). A mixture of
0.35 g of compound IV, 0.25 g of 1-naphthylacetic
acid (VI), and 0.2 g of zinc oxide was charged into
a quartz test tube, and the mixture was heated for
30 min at 340 C. The melt was cooled, crushed, and
extracted with benzene in a Soxhlet apparatus. The
benzene extract was evaporated till dryness, the dark-
green powder obtained was dissolved in chloroform
and subjected to column chromatography on
aluminum oxide of the II activity grade; elution with
EXPERIMENTAL
Electronic spectra of compounds obtained were
measured on spectrophotometer Hitachi UV-2000, IR
spectra were recorded on spectrophotometer Avatar
1
360 FT-IR in the region 4004000 cm from samples
1
pelletized with KBr. H NMR spectra (300 MHz,
TMS) and 13C NMR spectra (75 MHz) were register-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 39 No. 8 2003