Study of substituent effects on the photoconductivity of soluble 2,(3)- and 1,(4)-substituted phthalocyaninato- and naphthalocyaninatotitanium(IV) oxides

Article abstract of DOI:10.1021/ja981644y

Soluble alkyl (II, 8a,b), fluoroalkyl (4a), and fluoroalkoxy (4b,c, 8c) 1,(4)- or 2,(3)-substituted phthalocyaninato- and linear 2,(3)- and angular 1,(2)-annulated naphthalocyaninatotitanium(IV) oxides 10, 12, and 14 were synthesized and characterized wit

Full text of DOI:10.1021/ja981644y

J. Am. Chem. Soc. 1998, 120, 11663-11673
11663
Study of Substituent Effects on the Photoconductivity of Soluble
2,(3)- and 1,(4)-Substituted Phthalocyaninato- and
Naphthalocyaninatotitanium(IV) Oxides
Go1tz Winter,† Heino Heckmann,† Peter Haisch,† Wolfgang Eberhardt,† Michael Hanack,*,†
Larry Lu1er,‡ Hans-Joachim Egelhaaf,‡ and Dieter Oelkrug*,‡
Contribution from the Institut fu¨r Organische Chemie, Lehrstuhl fu¨r Organische Chemie II, Auf der
Morgenstelle 18, and Institut fu¨r Physikalische Chemie, Auf der Morgenstelle 8, UniVersita¨t Tu¨bingen,
D-72076 Tu¨bingen, Germany
ReceiVed May 11, 1998
Abstract: Soluble alkyl (II, 8a,b), fluoroalkyl (4a), and fluoroalkoxy (4b,c, 8c) 1,(4)- or 2,(3)-substituted
phthalocyaninato- and linear 2,(3)- and angular 1,(2)-annulated naphthalocyaninatotitanium(IV) oxides 10,
12, and 14 were synthesized and characterized with regard to their spectroscopic, photophysical, and
photochemical properties. While alkyl- and fluoroalkoxy-substituted compounds are highly soluble in nonpolar
solvents, e.g., hexane, fluoroalkyl-substituted compounds are better soluble in polar aprotic solvents such as
acetone. The stability against photooxidation in solution is enhanced on going from alkylated phthalocyanines
1,(4)-(C5H11)8PcTiO (8a), 1,(4)-(C6H13)8PcTiO (8b), and 2,(3)-(C4H9)8PcTiO (II) to fluorinated phthalocyanines
2,(3)-(CF3)4PcTiO (4a), 2,(3)-(CF3CH2O)4PcTiO (4b), and 2,(3)-(CF3CH2O)8PcTiO (4c), from phthalocyanines
to naphthalocyanines (tert-butyl)4-2,(3)-NcTiO (10), 1,(2)-NcTiO (12), and (tert-butyl)4-1,(2)-NcTiO (14), and
on going from 2,(3)-substituted 4a-c to 1,(4)-substituted phthalocyanines 8a-c. Thin films of these compounds,
prepared by either vacuum deposition or spin casting, are classified into three types according to increasing
intermolecular π-π interactions. Type R films, characterized by absence of exciton splitting, are formed
from 1,(4)-substituted phthalocyanines 8a-c. These films show low dark conductivities and photoconductivities
and are considerably sensitive to photooxidation. Type â films, characterized by weak exciton splitting, are
formed from fluorinated phthalocyanines 4a-c as well as from rapidly deposited 2,(3)-substituted phthalo-
cyanines II and the unsubstituted PcTiO (I). These films show enhanced photoconductivity and are generally
more stable against photooxidation than type R films. Type γ films, formed by slow deposition of II, 10 and
unsubstituted phthalocyanine I, are classified by a largely red-shifted B-band absorbing in the near-IR. These
films are highly photosensitive as well as stabilized against photooxidation. Steady-state photoconductivities
and dark conductivities in thin films are strongly dependent on oxygen partial pressure. Alkylated PcTiO’s
such as 8a, 8b, and II are found to be p-type conductors (positive oxygen influence on conductivities) like
unsubstituted PcTiO (I), whereas angularly annulated naphthalocyanines such as 12 and 14 as well as fluorinated
PcTiO’s 4a-c are n-type conductors (negative oxygen influence on conductivity). These findings are
rationalized by comparison with experimental and theoretical literature data.
Introduction
Phthalocyanines represent an important class of organic
photoconductors extensively used in organic xerographic pho-
toreceptors, attracting considerable attention due to their high
photosensitivity in the near-infrared region (600-850 nm).1 In
particular, phthalocyaninatotitanium(IV) oxide (PcTiO (I),
Figure 1) merits close attention, since it is known to be a very
potent charge generation material (CGM).2a This property and
† Institut fu¨r Organische Chemie, Eberhard-Karls Universita¨t Tu¨bingen.
‡ Institut fu¨r Physikalische Chemie, Eberhard-Karls Universita¨t Tu¨bingen.
(1) (a) Leznoff, C. C., Lever, A. B. P., Eds. Phthalocyanines, Properties
and Applications; VCH: New York, 1989-1996; Vols. 1-4. (b) Hanack,
M.; Lang, M. AdV. Mater. 1994, 6, 819. (c) Hanack, M.; Heckmann, H.;
Polley, R. In Methods of Organic Chemistry (Houben Weyl), 4th ed.;
Schaumann, E., Ed.; Thieme: Stuttgart, 1997; Vol. E9d, p 717.
(2) (a) Law, K.-Y. Chem. ReV. 1993, 93, 449. (b) Yonehara H.; Pac, C.
Mater. Res. Soc. Symp. Proc. 1994, 328, 301. (c) Fujimaki, Y.; Tadokoro,
H.; Oda, Y.; Yoshioka, H.; Homma, T.; Moriguchi, H.; Watanabe, K.;
Kinoshita, A.; Hirose, N.; Itami, A.; Ikeuchi, S. J. Imaging Technol. 1991,
17, 202. (d) Ghosez, P.; Coˆte´, R.; Gastonguay, L. Chem. Mater. 1993, 97,
8026. (e) Arishima, K.; Hiratsuka, H.; Tate, A.; Okada, T. Appl. Phys. Lett.
1982, 40, 279. (f) Mitzuguchi, J.; Rihs, G.; Karfunkel, H. R. J. Phys. Chem.
1995, 99, 16217.
Figure 1.
the possibility of preparing flexible films2 led to its use in
photostatic machines or GaAsAl laser printers. Research has
10.1021/ja981644y CCC: $15.00 © 1998 American Chemical Society
Published on Web 10/28/1998

11664 J. Am. Chem. Soc., Vol. 120, No. 45, 1998
Winter et al.
shown that the photocarrier generation efficiency of I and related
compounds depends not only on the central metal atoms but
also on the crystal structure,2f,3,4 while different polymorphs of
the same molecular materials usually have quite different
photoconductive properties. I shows this kind of polymorphism.
Unsubstituted I was synthesized first in 1963 by Taube,5a while
we published for the first time the crystal structures of two
polymorphs of I in 1982, phase I (monoclinic; P21/c, Z ) 4)
and phase II (triclinic; P1h, Z ) 2).6 A mixture of phases I and
II is obtained by using the synthesis of I of Block and Meloni.5b
In 1987, the photoconducting properties of I were described,7
and since 1991, I has found use as a CGM in photostatic
machines. The investigation of the photoconductivity in the
various polymorphs of PcTiO has been documented in a large
number of patents.8 There are different types of nomenclature
of the polymorphs in the literature: I, II, III, IV; A, B, C, Y; or
â, R, m, γ, respectively, which are used synonymously. Of
particular interest is the polymorph usually referred to as
Y-PcTiO (I), with a characteristic X-ray powder diffraction peak
at 27.2,2a,7b,c showing quantum efficiencies of carrier generation
approaching unity at high fields.1,2a,3,9 Nalwa et al. achieved a
phase transformation of the amorphous phase to the phases I,
II, and Y by vapor treatment.10 Rietveld analyses of phase Y
have been done by carrying out the refinement in a monoclinic
unit cell9b as well as in a triclinic cell.11 Molecular modeling
calculations12 pointed to the fact that the results of the
monoclinic refinement are in better agreement with the observed
diffraction pattern. The molecular arrangement in phase Y is
similar to that of phase I and characterized by a void between
two adjacent molecules.9,13 Phase III (m-) PcTiO is available
on acid pasting with octachloro-PcTiO and is characterized by
an interplanar distance of d ) 3.8 Å.14 Additionally, an
amorphous phase has been described by several authors.15
Yamashita et al. investigated the phase-selective formation of
PcTiO films depending on substrate temperature and evaporation
rate,15a and temperature-dependent absorption spectra of different
polymorphs of I have been published.13 Gulbinas et al.16 found
by means of fluorescence and photocurrent measurements
(exciton-exciton annihilation) that charge carriers are generated
during only a short time interval, much shorter than the
fluorescence-state lifetime after the exciton was created. The
samples were prepared by dispersing I in polyvinylbutyral
solution and coating onto a glass slide with transparent
conductive SnO2. The authors did not specify the type of
polymorph they investigated.16 Hinch and Voll17 obtained high
photosensitivity in the near-infrared and the visible spectral
regions by using a mixture of charge generation pigments such
as phthalocyaninatotitanium oxide and indium with different
axial ligands (O2-, Cl-, OH-), which were prepared by
coprecipitation from organic solvent/trifluoroacetic acid solution.
The electrical data of these composite compounds indicate that,
for example, PcInCl can be incorporated into the X-form (Y-
phase) of the I lattice at high concentrations with minimal
change in photosensitivity.17 Recently, Popovic et al.18 pointed
out that the relative positions of neutral and CT excited states
are a primary determinant of high carrier generation efficiency.
When the CT state is close to or below the lowest lying neutral
excited singlet state in the Y-phase of I, high carrier generation
efficiencies are observed. A general methodology, based on
time-resolved fluorescence quenching measurements, is pro-
posed to determine the neutral or CT character of a state
involved in charge generation.18
In our preceding studies, we described the synthesis and some
photophysical as well as photochemical properties of soluble
phthalocyaninatotitanium oxides [2,(3)-R8PcTiO], with R )
propyl, butyl (II) (Figure 1), pentyl, ethyloxy, pentyloxy (III),
and octyloxy substituents in the periphery of the phthalocyanine
ring.19a Compared to unsubstituted I, these compounds are
highly soluble in organic solvents, which allows purification
by column chromatography and preparation of thin films by
spin coating. The observed photooxidation of these compounds
in solution can be suppressed by exclusion of oxygen.
In the present study, we compare the photoconductivities of
different 2,(3)- and 1,(4)-substituted phthalocyaninato- and linear
2,(3)- and angular 1,(2)-naphthalocyaninatotitanium(IV) oxides
in order to contribute new information for a better understanding
of the carrier generation process. As we have already shown
in our previous papers,19 substitution in the periphery of the
phthalocyanine macrocycle not only affects the electronic states
but also produces structural changes in the solid phase. It was
observed by many authors that the photoconductivity of
unsubstituted I increases on going from the amorphous to the
crystalline phase.1,2a,4 Mizuguchi et al.2f investigated the
(3) Saito, T.; Sisk, W.; Kobayashi, T.; Suzuki, S.; Iwayanagi, T. J. Phys.
Chem. 1993, 97, 8026.
(4) (a) Popovic, Z. D.; Hor, A. M. Mol. Cryst. Liq. Cryst. 1993, 228,
75. (b) Popovic, Z. D. Chem. Phys. 1984, 86, 311. (c) Popovic, Z. D. J.
Chem. Phys. 1982, 76, 2714.
(5) (a) Taube, R. Z. Chem. 1963, 3, 194. (b) Block, R.; Meloni, E. G.
Inorg. Chem. 1965, 4, 111.
(6) Hiller, W.; Stra¨hle, J.; Kobel, W.; Hanack, M. Zeitschr. Kristallogr.
1982, 99, 173.
(7) (a) Klofta, T. J.; Danziger, J.; Lee, P.; Pankow, J.; Nebesny, K. W.;
Armstrong, N. R. J. Phys. Chem. 1987, 91, 5646. (b) Itami, A.; Kinoshita,
A.; Watanabe, K. (Konica Co.). Jpn. Kokai Tokkyo Koho, 04184448, 1992;
Chem. Abstr. 1992, 118, 49228z. (c) Itami, A.; Kinoshita, A.; Watanabe,
K. (Konica Co.). Jpn. Kokai Tokkyo Koho, 04184449, 1992; Chem. Abstr.
1992, 118, 49229a.
(8) (a) Yoshizawa, H.; et al. (Konica Co.). Jpn. Kokai Tokkyo Koho,
04264450, 1992; Chem. Abstr. 1993, 119, 37483m. (b) Mayo, J. D.; Duff,
J. M. (Xerox Corp.). 5164493, 1992; Chem. Abstr. 1993, 118, 61527d. (c)
Kinoshita, A.; et al. (Konica Co.). Jpn. Kokai Tokkyo Koho 0335064, 1991;
Chem. Abstr. 1991, 115, 218800a. (d) Yamazaki, I.; et al. (Canon K. K.).
Jpn. Kokai Tokkyo Koho 0384068, 1991; Chem. Abstr. 1991, 115, 194202d.
(e) Yamazaki, Y. (Olympus Optical Co., Ltd.). Jpn. Kokai Tokkyo Koho
0321669, 1991; Chem. Abstr. 1991, 114, 256954r. (f) Enokida, T. (Toyo
Ink Mfg. Co., Ltd.). Jpn. Kokai Tokkyo Koho 01299874, 1989; Chem. Abstr.
1990, 113, 14769w. (g) Miyamoto, E.; et al. (Mita Industrial Co., Ltd.).
Eur. Pat. Appl. 314100, 1989, Chem. Abstr. 1989, 111, 164174w.
(9) (a) Oka, K.; Okada O.; Iijimaim, M. Jpn. J. Appl. Phys. 1993, 32,
3556. (b) Oka, K.; Okada, O.; Nukada, K. Jpn. J. Appl. Phys. 1992, 31,
2181.
(15) (a) Yamashita, A.; Maruno, T.; Hayashi, T. J. Phys. Chem. 1994,
98, 12695. (b) Ghosez, Ph.; Cote´, R.; Gastonguay, L.; Veilleux, G.; Dene´s,
G.; Dodelet, J. P. Chem. Mater. 1993, 5, 1581.
(16) Gulbinas, V.; Jakubenas, R.; Pakaluis, S.; Undezenas, A. AdV. Mater.
Opt. Electron. 1996, 6, 412-414.
(17) Hinch, G. D.; Voll, K. A. Proc. SPIE-Int. Soc. Opt. Eng. 1996,
2850, 181.
(10) Nalwa, H. S.; Saito, T.; Kakuta A.; Iwayanagi T. J. Phys. Chem.
1993, 97, 10515.
(11) Bluhm, T.; Mayo, J.; Hamer, G.; Martin, T. Proc. SPIE-Int. Soc.
Opt. Eng. 1992, 1670, 160.
(12) Hinch, G. D.; Haggquist, G. W. Proc. SPIE-Int. Soc. Opt. Eng. 1997,
3144, 16.
(18) (a) Popovich, Z. D.; Khan, M. I.; Atherton, S. J.; Hor, A.-M.;
Goodman, J. L. J. Phys. Chem. B 1998, 102, 657. (b) Popovich, Z. D.;
Khan, M. I.; Atherton, S. J.; Hor, A.-M.; Goodman, J. L. In Electrical and
related properties of organic solids; Nunn, R. W., et al., Eds.; Xerox
Corp.: The Netherlands, 1997; p 207.
(13) (a) Saito, T.; Iwakabe, Y.; Kobayashi, T.; Suzuki, S.; Iwayanagi,
T. J. Phys. Chem. 1994, 98, 2726. (b) Okada, O.; Klein, M. L. J. Chem.
Soc., Faraday Trans. 1996, 92, 2463.
(14) Enokida, T.; Hirohashi, R.; Nakamura, T. J. Imaging Sci. 1990, 34,
234.
(19) (a) Haisch, P.; Winter, G.; Hanack, M.; Lu¨er, L.; Egelhaaf, H.-J.;
Oelkrug, D. AdV. Mater. 1997, 9 (4), 316. (b) Oelkrug, D.; Lu¨er, L.;
Egelhaaf, H.-J.; Hanack, M.; Haisch, P.; Heckmann, H.; Winter, G. Proc.
SPIE-Int. Soc. Opt. Eng. 1997, 3144, 4. (c) Egelhaaf, H.-J.; Lu¨er, L.;
Oelkrug, D.; Winter, G.; Haisch, P.; Hanack, M. Synth. Met. 1997, 84, 897.

Classification of Substituted Pc- and NcTiO’s
J. Am. Chem. Soc., Vol. 120, No. 45, 1998 11665
influence of intermolecular interactions on the optical absorption
spectra of single crystals (phases I and II) and evaporated films
(amorphous phase, I, II, and Y) regarding molecular distortion
and interplanar π-π interactions, concluding that the π-π
interaction is quite strong in phase II, while it is relatively weak
in phase I and the amorphous phase. We could confirm this
behavior for the substituted analogue,19a observing that only for
the 2,(3)-(C4H9)8PcTiO (II) is a successful phase transformation
achieved. Additionally, we investigated the degradation pro-
voked by the presence of oxygen of the substituted PcTiO’s by
varying ambient conditions and the type of solvent. We found
that air-saturated solutions of these PcTiO undergo photooxi-
dation according to first-order kinetics, whereas deoxygenated
solutions are stable.19a In the case of vapor-deposited films,
only the crystalline phase, which we were able to show in the
case of II, is stable with respect to photooxidation.
Scheme 1
The aim of our ongoing research is to determine the influence
on the photoconductivity of different types of substituents as
well as of an enlarged π-electron system (naphthalocyanines
instead of phthalocyanines) in these complexes. In the first step,
we introduced electron-withdrawing substituents such as fluo-
roalkyl or fluoroalkoxy groups in the 1,(4)- or 2,(3)-positions
of the phthalocyanine. These substituents increase both the
oxidation potentials and the stability of the macrocyclic systems
against photooxidation in solution.1 In the case of the naph-
thalocyanine titanium(IV) oxides, we compared the tetra(tert-
butyl)-substituted 1,(2)-naphthalocyanine (14) with the tetra(tert-
butyl)-substituted 2,(3)-naphthalocyanine (10) with regard to
their HOMO and LUMO positions and their stability and
photoconductivity. Thin films of the substituted PcTiO, pre-
pared by either vacuum deposition or spin casting, are classified
into three types according to increasing intermolecular π-π
interactions. In this paper, we define type R, â, and γ films:
type R films, characterized by absence of exciton splitting, type
â films, characterized by weak exciton splitting, and type γ
films, classified by a largely red-shifted B-band absorbing in
the near-IR.
Scheme 2
Synthesis
The synthetic routes to the precursors of the substituted
phthalocyaninatotitanium(IV) oxides 4a-c, 8a-c (dinitriles
3b,c20 and isoindolines 7a-c21), are shown in Scheme 1. The
trifluoromethyl- and 2,2,2-trifluoroethoxy-substituted phthalo-
cyaninatotitanium(IV) oxides (4a-c) are obtained from the
dinitriles 3a-c20 and titanium(IV) butoxide in 1-octanol or
1-pentanol, respectively, under the conditions given in Scheme
2.
The unsubstituted 1,(2)-naphthalocyaninatotitanium(IV) oxide
(12) has already been described in the literature.22 The highly
soluble tetra(tert-butyl)-substituted 2,(3)-naphthalocyaninato-
titanium(IV) oxide (10) (mixture of isomers) is synthesized, and
its photoconductivity is compared with that of the PcTiO (I).
We also synthesized 12 and the tetra(tert-butyl)-substituted
1,(2)-naphthalocyaninatotitanium(IV) oxide (14) (both mixtures
of isomers as described for 1,(2)-NcFe23). As a result of their
comparable electronic properties, we did not expect effects much
different from I for unsubstituted 12.
1,(4)-(C5H11)8PcTiO (8a) and 1,(4)-(C6H13)8PcTiO (8b) are
synthesized by reacting the corresponding substituted 4,7-di-
(n-alkyl)-1,3-diimino-1,3-dihydroisoindolines 7a,b with tita-
nium(IV) butoxide (Scheme 2), whereas the 2,2,2-trifluoroethoxy-
substituted compound 8c is obtained by treating the corresponding
4,7-bis(2,2,2-trifluoroethoxy)-1,3-diimino-1,3-dihydroisoindo-
lines (7c) with titanium tetrachloride in 1-chloronaphthalene with
addition of naphthalene to prevent the halogenation of the
macrocycle.
(20) Pawlowski G.; Hanack, M. Synth. Commun. 1981, 11, 351.
(21) McKeown, N. B.; Chambrier, I.; Cook, M. J. J. Chem. Soc., Perkin
Trans. 1 1990, 1169.
(22) (a) Tai, S.; Hayashida, S.; Hayashi, N. (Hitachi Chemical Co., Ltd.).
U.S. Patent 4.842.970, 1988. (b) Numa, T. (Nippon Kayaku Co., Ltd.). Jpn.
Kokai Tokkyo Koho 63154767, 1988; Chem. Abstr. 1989, 110, 116679x.
(23) Hanack, M.; Renz, G.; Stra¨hle, J.; Schmid, S. J. Org. Chem. 1991,
56, 3502.
To synthesize 10 (mixture of isomers), the dinitrile 924 was
heated with titanium(IV) butoxide and DBU in a sealed ampule
(24) Kovshev, E. I.; Puchnova, V. A.; Luk’yanets, E. A. Zh. Org. Khim.
1971, 7, 369; J. Org. Chem. USSR 1971, 364.

11666 J. Am. Chem. Soc., Vol. 120, No. 45, 1998
Winter et al.
Scheme 3
under nitrogen (Scheme 2). To prepare pure unsubstituted 12,
the corresponding 1,2-dicyanonaphthalene25 (11) was treated
with titanium(IV) butoxide and urea in n-octanol (Scheme 3).
To avoid the formation of the metal-free naphthalocyanine, urea
is a necessary additive.26
In Scheme 3, the synthesis of 14 is carried out starting with
1,2-dicyano-7-tert-butylnaphthalene (13), which is reacted with
titanium(IV) butoxide. Compared to unsubstituted I,19 com-
pounds 4b and 8c are soluble in acetone and THF, while 8a,b
and 10 are highly soluble in organic solvents, e.g., in THF,
toluene, and dichloromethane, which allows purification by
column chromatography and preparation of thin films by spin
coating. The trifluoromethyl (4a) and the 2,2,2-trifluoroethoxy
(4b) substituted PcTiO’s are only slightly soluble in, e.g.,
acetone, DMF, or DMSO.
Figure 2. Electronic absorption spectra of 8b, 8c, 4b, 12, 10, and II
in THF solutions (labeled by “S”) and thin films. Films of 8b, 8c, 4b,
and 10 were prepared by spin-coating, films of 12 by vapor deposition
without annealing, and films of II by vapor deposition at a substrate
temperature of T ) 140 °C (curve B) and T ) 25 °C (curve AH/AL).
UV-Visible Absorption Spectra
Figure 2 and Table 1 present electronic absorption data in
the Q-band regime measured in tetrahydrofuran solutions and
in vapor-deposited or spin cast films. The extinction coefficients
of the Q-band maxima have been determined to be ꢀ ) (2 (
0.2) × 105 L mol-1 cm-1. Starting from unsubstituted I, the
absorption maxima Qm in solution shift upon substitution to
longer wavelengths because of increasing dielectric polariz-
abilities of the phthalocyanine units. The strongest bathochro-
mic shift is obtained with linear naphthalene subunits in
combination with peripheral tert-butyl groups (10). When
angular naphthalene subunits without peripheral substituents are
introduced as in 12, the shift reduces to very small values. This
effect has been also theoretically investigated in the metal-free
phthalocyanine.27 The second strongest bathochromic shifts of
the PcTiO are obtained with substituents in 1,(4)-positions of
the benzene rings (8a-c) that allow conjugation with the 18π-
annulene system. The shifts decrease from alkoxy to alkyl
substituents. The smallest bathochromic shifts are obtained with
substituents in 2,(3)-positions of the benzene or naphthalene
rings (II, 4a-c, 14) with no conjugation. The shifts reduce in
the series R ) alkyl (II), alkoxy (III), (trifluoroethoxy)4 (4b),
(trifluoroethoxy)8 (4c), and trifluoromethyl (4a). In the last
compound, the Q-band is already shifted slightly hypsochromic
against the reference I because of the strong (-I)-effect of the
CF3 groups.
Table 1. Q-Band Absorption Maxima of Phthalocyaninato- and
Naphthalocyaninatotitanium(IV) Oxides in THF and Thin Films (d
≈ 50 nm) Ordered According to Increasing Transition Energies in
Solutiona
THF solutions
thin films
compound
(tert-butyl)4-2,(3)-NcTiO (10) 799.5 758
Qm (nm) AH (nm) AL (nm) B (nm)
818
(960)
836
1,(4)-(CF3CH2O)8PcTiO (8c)
1,(4)-(C6H13)8PcTiO (8b)
741.0
728.5
732.5
722
(tert-butyl)4-1,(2)-NcTiO (14) 709.0 (650)
718
715
731
2,(3)-(C4H9)8TiO (II)19a
1,(2)-NcTiO (12)
700.5 666
695.5 (657)
695.0
691.5 641
688.5 630
686.0 (650)
685.5 639
2,(3)-(C5H11O)PcTiO (III)19a
2,(3)-(CF3CH2O)4PcTiO (4b)
2,(3)-(CF3CH2O)8PcTiO (4c)
PcTiO (I)
(706)
720
713
854
2,(3)-(CF3)4PcTiO (4a)
(698)
a Positions of shoulders are given in parentheses.
in the subsequent discussion and should not be mixed up with
the depiction of polymorphs used in general for phthalocyanines.
The spectra of type R films (Figure 2) are very similar to the
corresponding solution spectra. The main maximum is only
slightly blue-shifted by ∆λ ) 5-10 nm against Qm in THF
solution, and the vibrational structure of the Q-band is preserved.
In some cases an additional weak peak AL appears, red-shifted
by ∆λ ) 30 nm against Qm. These spectra are typical for
1,(4)-substituted PcTiO’s (8b,c), where two of the eight sub-
stituents must be oriented perpendicularly to the phthalocyanine
plane for steric reasons, thus preventing close proximity and
High vacuum condensation of substituted PcTiO to solid films
produces new types of Q-bands, which are classified with respect
to the relative shift against the Q-band maxima Qm in solution
as type R, â, and γ. This nomenclature is used for convenience
(25) Bradbrook E. F.; Linstead, R. P. J. Chem. Soc. 1936, 1739.
(26) Yao, J.; Yonehara, H.; Pac, C. Bull. Chem. Soc. Jpn. 1995, 68, 1001.
(27) Ort´ı, E.; Piqueras, M. C.; Crespo, R.; Bre´das, J. L. Chem. Mater.
1990, 2, 110.

Classification of Substituted Pc- and NcTiO’s
J. Am. Chem. Soc., Vol. 120, No. 45, 1998 11667
Table 2. Steady-State Dark Conductivities and Photosensitivity Parameters a of Thin Films (d ) 15-70 nm) as Well as the Ratios of Dark
Conductivities in Oxygen by Dark Conductivities under Vacuum, Measured at 120 °Ca
dark conductivity σd
σd,vacuum
σ
d(oxygen)/σd(vacuum)
,
irradiation
wavelength, nm
compound
PcTiO (I)
2,(3)-(C4H9)8TiO (II)
(tert-butyl)4-2,(3)-NcTiO (10)
(tert-butyl)4-1,(2)-NcTiO (14)
1,(2)-NcTiO (12)
1,(4)-(C6H13)8PcTiO (8b)
1,(4)-(CF3CH2O)8PcTiO (8c)
2,(3)-(CF3CH2O)4PcTiO (4b)
2,(3)-(CF3)4PcTiO (4a)
T ) 20 °C
T ) 120 °C
T ) 120 °C
avacuum
film type
2 × 10-13
7 × 10-10
5 × 10-11
4 × 10-9
1 × 10-7
≈10-9
4000c
>350c
1000d
<1
1× 10-6
710
710
850
717
710
722
690
640
640
γ
γ
γ
â
â
R
R
â
â
<10-13
2 × 10-8
5 × 10-7
8 × 10-8
1.3 × 10-8
3 × 10-9
5 × 10-10
1.3 × 10-8
9 × 10-9
4 × 10-11
4 × 10-9
2 × 10-12
<5 × 10-12
<10-11
<1
2 × 10-11
6 × 10-11
6 × 10-9
6 × 10-10
b
≈1/1000
<1/100
<1/120
<10-11
6 × 10-12
a Values of σd are given in S cm-1 and values of a in S cm W-1, as derived from σ ) σd + aL. Irradiation intensity L ) 400 µW cm-2. Irradiation
wavelength in nm and film type is also given. b No steady-state value due to rapid decomposition. c At 20 °C. d At 50 °C.
π,π-overlap of adjacent molecules in the solid state.28 The
distance d of neighboring phthalocyanine planes in the metal-
free analogue of 8b was determined to be d ) 8.5 Å, more
than twice the value for I (d ) 3.3 Å).5 The spectra of type â
films (Figure 2) are considerably broadened against the mono-
mer. Two structureless absorption regions with maxima AH and
AL are formed at the high energetic (AH) and low energetic (AL)
sides of Qm. The energy splittings AH - AL ) 0.1-0.15 eV
(∆λ ) 50-75 nm) can be assigned within the molecular exciton
model to short-range transition dipole-dipole interactions in
partly ordered amorphous phases. The difference AH - AL is
very sensitive to the distance d and the intermolecular orientation
of neighboring phthalocyanine planes. In the point dipole
approximation, the energy splitting is proportional to d-3, so
that hardly any splitting is expected in type R films. In type â
films, the energy splittings increase by a factor of 5-10 due to
closer intermolecular distances. Either planes of adjacent
molecules must be tilted, which makes both transitions AH and
AL allowed, or the films are formed partly from sandwich
aggregates (H-aggregates) and tiled roof aggregates (J-ag-
gregates). As will be shown later, AH is definitely more sensitive
to photodecomposition than AL, so that it is reasonable to assign
the two maxima to different subphases which are simultaneously
present in the films. Type â films are formed by fast deposition
of unsubstituted and 2,(3)-substituted PcTiO. Fluorine-contain-
ing substituents support the intensity of AH, while pure
hydrocarbon chains support AL. By annealing or slow deposi-
tion, the latter PcTiO can be transferred into type γ films (Figure
2 bottom), with an additional B-band in the near-infrared. From
the energy difference against solution, Qm - B ) 0.3 eV, this
band arises from dipole-dipole interactions in crystalline phases
forming extended J-aggregates. In the case of unsubstituted I,
the appearance of a B-band in the optical spectrum corresponds
to the crystalline phase II.2f,9a The presence of a similar crystal
structure in type γ films of substituted PcTiO is not proven
since single crystals large enough for X-ray diffraction could
not be grown up to now. From EXAFS, the intermolecular Ti-
Ti distance of a powder sample of II was determined to be d )
4.1 Å. To a first approximation, this value represents also the
distance of neighboring phthalocyanine planes so that exciton
splittings comparable to that of I can be expected. The
transformation into type γ films can be achieved most easily
with I, to a high degree with II,19a and partly with 10. However,
we did not succeed until now in transforming fluorinated
compounds into type γ films.
Dark Conductivity
Thin films of the PcTiO described in this paper are very weak
electric conductors with dark conductivities in the range of σd
≈ 10-11-10-9 S cm-1 (in vacuo at T ) 120 °C). Linear I/V
characteristics have been determined up to field strengths E )
104 V/cm. As can be seen from Table 2, the dark conductivities
are strongly dependent not only on temperature but also on the
oxygen partial pressure of the surrounding gas phase. The
oxygen dependence of conductivity was determined at T ) 120
°C since the kinetics of interaction with oxygen is faster at
elevated temperatures, and absolute conductivity values are
higher than those at room temperature.
Conductivity data in vacuo at T ) 120 °C are shown in the
second column of Table 2. The dark conductivities of 8b,c and
of II are about 1 order of magnitude lower than that of I. The
conductivities of 4a and 12 are comparable to that of I. Finally,
10, 14, and 4b are better dark conductors than I.
The third column of Table 2 presents the influence of oxygen
exposure (p(O2) ) 1 bar) on the dark conductivities. The
conductivities increase with I and its alkylated as well as linearly
annulated analogues. In contrast, the conductivities decrease
with fluorinated compounds 4a,b and 8c and with angularly
annulated naphthalocyanines 12 and 14. Figures 3 and 4 show
typical examples of positive and negative influence of oxygen
on the dark conductivities of phthalocyanine films. The positive
influence, measured at T ) 50 °C with a film of 10, is rather
slow, with rise times of τ ) 103-104 s (Figure 3). However,
the kinetics of oxygen uptake can be significantly accelerated
upon irradiation into the Q-bands of the samples. This can be
shown by measuring dark conductivities after specified periods
of irradiation during oxygen exposure (see inset of Figure 3).
An example of negative oxygen influence is presented in
Figure 4 in a semilogarithmic scale. The first three half-values
of σd are observed after exposure times of t1/2 ≈ 10 s. Then
the decay curve slows down, but its negative slope is still big
enough to reduce σd after t ) 200 s to about 2% of its value in
a vacuum. The effect is reversible to a high degree since, after
annealing in a vacuum, σd recovers to 90% of its original value.
The experimental results are correlated in the following
paragraphs to the concentration Nd and mobility µ of charge
carriers. Since the autoionization constant Kd of the reaction
2Pc f Pc+ + Pc- is very low in materials formed from closed-
shell neutral phthalocyanines, Nd depends strongly on the
concentration of ionized donor or acceptor impurities. Dominant
and unavoidable impurities under “clean” conditions are water
and molecular oxygen. It is well known that oxygen favors
(28) Chambrier, I.; Cook, M. J.; Helliwell, M.; Powell, A. K. J. Chem
Soc., Chem. Commun. 1992, 444.

11668 J. Am. Chem. Soc., Vol. 120, No. 45, 1998
Winter et al.
donors, Pc + D f Pc- + D+, and support n-type conductance.
In those cases, exposure to oxygen will reduce conductivity,
because the negative majority charge carriers formed by D are
partly compensated by the positive charge carriers formed by
O2.
Schlettwein and Armstrong32 pointed out the importance of
the HOMO position on phthalocyanine conductivity and esti-
mated the transition from p- to n-conductance at EHOMO ≈ -6.5
eV vs vacuum. From UPS spectra, the experimental binding
energy of the parent compound I was found by these authors at
EHOMO ≈ -6.3 eV. Extension of the π-electron system as in
10 raises the HOMO level by about 0.4 eV.27 The mesomeric
extension in 10 is supported by additional positive inductive
(+I)-effects of the alkyl substituents. These substituents alone
are also able to slightly raise the HOMO level, so that finally
all compounds forming type γ films (I, II, and 10) are p-type
conductors with a strong positive oxygen influence on dark
conductivity (see the high σox/σvac ratios of these compounds
in Table 2).
On the other hand, angularly annulated aromatic rings as in
1,(2)-naphthalocyanines 12 and 14 stabilize the HOMO level
against I by about -0.3 eV.27 Thus, the HOMO energy of 12
is located below -6.5 eV, where the transition from p- to n-type
conductance is expected, and correspondingly the conductivity
of 12 decreases upon oxygen exposure (see Table 2). Also,
stabilization of the HOMO level by electron-withdrawing
fluorine substituents as in 8c, 4b, and 4a supports n-type
conductance.
Figure 3. Dark current Id of 10 as a function of oxygen exposure time
t(O2). Lower curve, oxygen exposure in the dark; upper curve, oxygen
exposure under illumination of λ ) 850 nm; dark currents measured
after illumination periods indicated by full points. The original
measurement for curve 2 is displayed in the inset. Wavelength of light
pulses λ ) 850 nm. p(O2) ) 1 bar, U ) 50 V, T ) 50 °C for all
measurements.
In addition to NV, also the charge carrier mobilities are
affected by the substituents of PcTiO. The highest values are
found in unsubstituted I with µ ≈ 10-3 cm2 V-1 S-1, which is
still orders of magnitude lower than those in perfect organic
crystals with negligible trap densities but orders of magnitude
higher than those in films of conjugated polymers or oligomers,
e.g., polyphenylenevinylenes or polythiophenes.26 Besides the
retardation effect of traps, all electronically inactive substituents
slow the electron hopping rates between neighboring phthalo-
cyanines because of larger intermolecular distances. Thus,
charge carrier mobilities in type R films are expected to be
orders of magnitude lower than those in type γ films, which is
another reason for the measured low dark conductivities in 8b,c.
Photoconductivity
Upon irradiation into the Q-bands of the samples, excess
carriers are induced, and conductivities increase roughly linearly
with light intensity L according to
Figure 4. Dark current decay of fluorinated compound 4a upon
exposure to 1 bar oxygen at 120 °C after annealing for 16 h at T )
150 °C. t ) 0 refers to start of oxygen exposure.
σ ) σd + aL
(1)
- 29-32
formation of Pc+ according to Pc + O2 f Pc+ + O2
.
This reaction also reduces the Pc- concentration of the autoion-
ization equilibrium and leads, in many examples, to p-type
conductance. From transient oxygen-induced dark conductivity,
a CT complex PcO2 has been postulated as precursor for charge
separation by oxygen.33 The formation tendency of this complex
increases with increasing HOMO energy (i.e., decreasing
ionization energy) of the phthalocyanine in the solid. Low
HOMO energies, on the other hand, favor the interaction with
where a is the photosensitivity constant in units of S cm W-1
.
The product aL is referred to as photoconductivity σp. Within
the Q-band, the photosensitivity constant is independent of
irradiation wavelength, indicating the vibrationally relaxed S1
state as being a precursor for free charge carrier formation, as
34
has been found for PcH2 and PcTiO.18
Photoconductivities rise in the series type R films < type â
films < type γ films (see Table 2). The dependences of σp on
oxygen pressure are qualitatively the same as in the dark,
although less pronounced. In films of alkylated compounds and
I, σp rises upon oxygen exposure, whereas it decreases in
fluorinated compounds and angularly annulated naphthalocya-
nines.
(29) Wo¨hrle, D.; Kreienhoop, L.; Schlettwein, D. In Phthalocyanines,
Properties and Applications; Leznoff, C. C., Lever, A. B. P., Eds.; VCH:
New York, 1996; Vol. 4, p 223.
(30) Jasunaga, H.; Kojima, K.; Johda, H.; Takeya, K. J. Phys. Soc. Jpn.
1974, 37, 1024.
(31) Musser, M. E.; Dahlberg, S. C. Surf. Sci. 1980, 100, 605.
(32) Schlettwein, D.; Armstrong, N. R. J. Phys. Chem. 1994, 98, 11771.
(33) Lu¨er, L.; Egelhaaf, H.-J.; Oelkrug, D. Opt. Mater. 1998, 9, 454.
(34) Noolandi, J.; Hong, K. M. J. Chem. Phys. 1979, 70, 3230.

Classification of Substituted Pc- and NcTiO’s
J. Am. Chem. Soc., Vol. 120, No. 45, 1998 11669
Photoinduced charge carrier formation in organic solids is
known to afford impurities such as molecular O2 acting as traps
for diffusing excitons, whereupon an exciplex (Pc+O2-)* is
formed. Due to high intrinsic polarization, this exciplex
facilitates charge separation.22,26,27 The existence of (Pc+O2-)*
in I and 10 was shown in transient conductivity measurements,
although it has not yet been spectroscopically confirmed. We
found that the formation of a ground-state CT complex
(Pcδ+O2δ-) during oxygen exposure is strongly accelerated by
irradiation with light of Q-band absorption.26 Popovich et al.18
showed the influence of water vapor on photoconductivity in
PcTiO.
Crucial parameters for efficient exciplex formation are high
exciton diffusion lengths and high densities of photoactive
impurities. The exciton diffusion length strongly depends on
the intermolecular distance d. As has already been discussed,
the annulene systems in solids of 1,(4)-substituted compounds
(type R films) have to be regarded as electronically isolated, d
being nearly 1 nm. Thus, electronic excitation tends to be local,
and exciton diffusion to an impurity is slow. Therefore, films
of 8b,c are very weak photoconductors. Type γ films of I, II,
and 10, on the other hand, display largely red-shifted B-bands
in the absorption spectra, indicating long-range order and hence
efficient exciton diffusion. Films of these compounds show
photoconductivities sufficiently high for applications in elec-
trophotographic devices.
Figure 5. Photooxidation of soluble compounds in air-saturated
solutions of THF under irradiation of light with λirr ) 670-730 nm
and intensity L ) 0.48 mW/cm-2. Absorbances were measured at the
Q-band maxima and normalized to Qmax ) 1.
The impurity density of molecular oxygen can be controlled
by the O2 partial pressure in the gas phase. Thus, photocon-
ductivities increase in p-type conducting films upon oxygen
exposure, since the density of charge separation centers forming
mobile Pc+ holes is raised. Experimentally, this behavior is
observed with films of I, II, and 10. In n-type conducting films
(4a, 4b, 12, 14, and 8c), on the other hand, any irradiation
induced Pc+ holes produced at charge separation centers
recombine with the negative majority carriers via the autoion-
ization equilibrium. Therefore, photoconductivity decreases in
n-conducting samples upon oxygen exposure.
Figure 6. 6: Dependence of the photochemical quantum yields φph
-6
of II in toluene (c ) 5 × 10
mol/L) as a function of oxygen
Photochemical Stability
concentration c(O2).
Stability in Solution. It is well known that π-conjugated
organic molecules are sensitive to photooxidation in oxygen-
containing solvents. The most important primary step is
activation of 3O2 to 1O2 via excitation energy transfer from the
excited conjugated molecule. In most phthalocyanines, the first
Table 3. Photooxidation Quantum Yields φph in Air-Saturated
Tetrahydrofuran (THF) Solutions and Thin Films (As-Deposited) at
Room Temperaturea
compound
PcTiO (I)
(tert-butyl)4-2,(3)-NcTiO (10)
(tert-butyl)4-1,(2)-NcTiO (14)
φph (THF)
φph (film)
3
1
2 × 10-6
triplet state Pc* lies energetically above the O2 state, so the
reaction
1.6 × 10-3
3 × 10-4
3 × 10-6
3O2
9
1,(4)-Substituted
Pc(S0)
9
hν8 1Pc* f 3Pc*
8 Pc(S0) + 1O2
(2)
1,(4)-(C6H13)8PcTiO (8b)
1,(4)-(CF3CH2O)8PcTiO (8c)
4.5 × 10-4
1 × 10-3
5 × 10-5
3 × 10-4
1
1
2,(3)-Substituted
is the main route for O2 formation. Thus, the amount of O2
is controlled by the intersystem crossing rate of 1Pc*, the lifetime
2,(3)-(C4H9)8TiO (II)
7 × 10-3
3 × 10-5
2,(3)-(CF3CH2O)4PcTiO (4b)
2,(3)-(CF3CH2O)8PcTiO (4c)
2,(3)-(CF3)4PcTiO (4a)
2.4 × 10-3
1.3 × 10-3
3.7 × 10-4
3 × 10-5
3
of Pc*, the oxygen concentration, and the solvent viscosity.
The subsequent attack of O2 on the π-electron system is also
1
9 × 10-6
controlled by solvent viscosity and possibly by shielding
substituents.
a Irradiation wavelength region λ ) 670-730 nm at Intensities of L
) 0.48 mW/cm2 in THF and L ) 0.65 mW/cm2 in films.
The kinetics of photodecomposition of dissolved Pc’s is
analyzed by the decay of Q-band absorbance as a function of
irradiation time and oxygen concentration. The decay follows
a first-order reaction over more than 90% of product disap-
pearance (Figure 5). Photodecomposition of II yields octa(n-
butyl)phthalimide as the clearly dominating reaction product
all Pc’s are photochemically very stable, which can be seen
from Figure 6, where the quantum yields of photodecomposition
φph have been plotted against the O2 concentration. Extrapola-
tion to oxygen-free solvents yields lim φph(c(O2)f0) ) 0.
Table 3 summarizes quantum yields of photodecomposition
in air-saturated solutions. The fastest decay is found with II,
whereas the 1,(4)-substituted PcTiO’s 8b,c are most stable
against photooxidation in solution. These variations of quantum
1
(identified by H NMR, 13C NMR, and MS), which supports
oxidative cleavage of the annulene ring as the main photo-
chemical reaction step. In the absence of dissolved oxygen,

11670 J. Am. Chem. Soc., Vol. 120, No. 45, 1998
Winter et al.
In films of the fluorinated PcTiO’s 4a, 4b, the optical spectrum
is found to change during photooxidation. In the early stages
of photooxidation (tirr < 104 s), AH disappears more rapidly than
AL. As a consequence, the initial values of φph for AH are higher
than those for AL in these samples. Over the whole measuring
time, φph is constant for AL; it decreases with time for AH.
The mechanism of photooxidation in films is not yet known.
1
No O2 formation could be found, and no intermediates have
yet been analyzed. Since exciplex formation and photooxidation
both occur in the same time domain (i.e., several days at room
temperature), it is possible that the exciplex (PcO2)* is a
precursor for both charge separation and photooxidation. The
latter process would then be an unavoidable parallel reaction
in oxygen-induced photoconductivity. p-Type conductors with
strong oxygen interaction would be more subject to photooxi-
dation than n-type conductors. Experimentally, this is confirmed
by comparing 2,(3)-substituted compounds of different HOMO
energies. The fluorinated compounds 4a,b with a stabilized
HOMO level are rather stable against photooxidation, while the
alkylated species II with an elevated HOMO level is decom-
posed more rapidly.
The other crucial parameter in controlling φph in thin films
is the diffusion coefficient of molecular oxygen DO . In PbPc,
2
DO ≈ 2 × 10-10 cm2 s-1 at T ) 465 K.36 A very tentative
2
extrapolation to room temperature yields DO ≈ 10-17-10-19
2
2
cm s-1, which means that oxygen attack is restricted to the
surface regions in crystalline phthalocyanines with closely
packed molecular units. Photochemical quantum yields in this
case are expected to be low and time-dependent, since interfacial
processes such as aggregation (growth of larger crystallites at
the expense of smaller ones) or passivation (surface deposition
of oxidation products) lead to a decrease of free surface with
time. The microcrystalline nature of I films is well known,9a
and passivation was also demonstrated with I by a progressive
retardation of oxygen sorption kinetics over several days at T
) 100 °C.37 The time dependence of φph of I (Figure 7b) is
thus reasonably explained. In amorphous systems, the diffusion
coefficient of oxygen is significantly increased due to introduc-
tion of large numbers of dislocations, yielding a quasi-
homogeneous distribution of molecular oxygen in the samples.
Therefore, φph values in these samples are expected to be high
and time-independent, as is the case with II (Figure 7a). The
amorphous nature of II can be indirectly deduced from the
absent contrasts in SEM micrographs and X-ray diffraction
Figure 7. Dependence of photochemical quantum yield φph on
irradiation time. Dots: measured values of φph for compounds as
indicated. (h) Data from bleaching of AH peak. (l) Data from bleaching
of the AL peak. Solid curves: fits according to φph ) at-n; 0 e n e
0.65. Film thicknesses d ≈ 50 nm, λirr ) 670-730 nm with intensity
L ) 0.65 mW/cm-2
.
yields are explained by electronic effects of the peripheral
substituents. Electron-donating substituents enhance the prob-
ability of photooxidation, and electron-withdrawing substituents
reduce it. With alkoxy and nitrile substituents, Sobbi et al.35
described a similar effect. Substituents in 1,(4)-positions show
also a stabilizing effect of about 1 order of magnitude against
2,(3)-positions; compare 4c with 8c, and II with 8b. Fluorina-
tion and angular annulation further increases photochemical
stability, as can be seen by comparing 8b with 8c, and II with
12, respectively.
plots.30 A further increase of DO is expected if the intermo-
2
lecular Pc-Pc distances are raised by spacer groups in 1,(4)-
positions pointing perpendicularly to the Pc plane as in 8b. This
sterical conformation favors photooxidation by molecular
oxygen dissolved in the free volume between the Pc units.
Summary
Stability of Films. Thin films of almost all compounds
described in this paper are stabilized against photooxidation by
about 2 orders of magnitude compared to the corresponding
THF solutions (see Table 3). Compound 8b, as the only
example, is destabilized in the films. As can be seen from
Figure 7a,b, the photochemical quantum yields of 8b and II
are independent of time (Figure 7a), whereas with 8c, 10, and
I, φph decreases with time according to the empirical formula
Soluble alkyl (II), fluoroalkyl (4a), and fluoroalkoxy (4b,c)
substituted phthalocyaninato- and naphthalocyaninatotitanium-
(IV) oxides 10, 12, and 14, substituted in 1,(4)- or 2,(3)-positions
of the aromatic rings, were synthesized and characterized with
regard to their spectroscopic, photophysical, and photochemical
properties to evaluate their possible use in electrophotographic
devices. The solubilities in organic solvents are sufficient for
spin casting of thin films. The measured photoconductivities
as well as the stabilities against photooxidation were found to
depend not only on the energetic HOMO positions of the film
φph ) bt-n; 0.3 e n e 0.6
(3)
(36) Yasunaga, H.; Kojima, K.; Yohda, H.; Takeya, K. J. Phys. Soc.
Jpn. 1974, 37, 1024.
(37) Lu¨er, L.; Egelhaaf, H.-J.; Oelkrug, D. Unpublished results.
(35) Sobbi, A. K.; Wo¨hrle, D.; Schlettwein, D. J. Chem. Soc., Perkin
Trans. 2 1993, 481.

Classification of Substituted Pc- and NcTiO’s
J. Am. Chem. Soc., Vol. 120, No. 45, 1998 11671
974m, 1063m, 1109m, 1159s, 1171s, 1182m, 1203w, 1254s, 1271m,
1292m, 1317m, 1408w, 1425w, 1441w, 1456w, 1491m, 1566m, 1574m,
constituting molecules but also on the charge and oxygen
transport properties, which are determined by the morphologies
of the films. Elevation of the HOMO level by introduction of
alkyl substituents in 2,3-positions or on going from phthalo-
cyanines to 2,3-naphthalocyanines leads to high photoconduc-
tivities due to positive oxygen influence (p-type conductance)
but also to enhanced photooxidation. Stabilization of the
HOMO by introduction of fluorinated substituents or on going
from phthalocyanines to 1,2-naphthalocyanines lowers the
sensitivity against photooxidation as well as absolute photo-
conductivity values due to negative oxygen influence (n-type
conductance).
Morphology control of the films is feasible by variation of
substituents as well as film deposition parameters. Thin films
of 1,4-substituted phthalocyanines with very weak intermolecu-
lar π-π interactions show low photoconductivities and are most
sensitive to photooxidation. Strongest intermolecular π-π
interactions are achieved by slow deposition of compounds with
high electron densities in their annulene systems, i.e., alkylated
2,3-substituted phthalocyanines and 2,3-naphthalocyanines as
well as the unsubstituted parent compound PcTiO. These films
show the highest photoconductivities and are stabilized against
photooxidation.
1607m, 2235m, 2955w, 3088w, 3117w cm-1
.
1H NMR (acetone-d6):
3
3
4
δ 4.95 (q, JHF ) 8.3 Hz, 2H, H-1), 7.61 (dd, J ) 8.9 Hz, J ) 2.8
4
3
Hz, 1H, H-a′), 7.80 (d, J ) 2.4 Hz, 1H, H-b), 8.05 (d, J ) 8.9 Hz,
1H, H-b′). 13C NMR (acetone-d6): δ 66.44 (q, JCF ) 36 Hz, C-1),
2
109.61 (C-c′), 115.97/116.30 (C-d/d′), 118.14 (C-c), 120.95/121.27 (C-
a′/b), 124.34 (q, 1JCF ) 277 Hz, C-2), 136.63 (C-b′), 161.27 (C-a). 19
F
3
NMR (CD3OD): δ -76.0 (t, JFH ) 8.6 Hz). MS (EI: m/z (relative
intensity) 226.2 (75) [M+]. Anal. Calcd for C10H5F3N2O: C, 53.11;
H, 2.23; N, 12.39. Found: C, 53.27; H, 2.59; N, 12.48.
2,9,16,23-Tetrakis(2,2,2-trifluoroethoxy)phthalocyaninatotitanium-
(IV) Oxide (4b). A mixture of 3b (1.5 mmol) and titanium(IV)
butoxide (3 mmol) was heated in a sealed ampule under a nitrogen
atmosphere to 150 °C for 7 h. The crude product was precipitated
with MeOH/H2O/EtOH (1:1:1) and further purified by column chro-
matography (silica gel, hexane/acetone (1:1)). The green fraction was
collected. After evaporation of the solvent under vacuum a green
residue was obtained which was washed again with EtOH and dried in
vacuo at 85 °C. Yield: 200 mg (55%), dark blue powder. IR (KBr):
1610s, 1487s, 1458s, 1431w, 1342s, 1288s, 1236vs, 1167vs, 1121s,
972s, 876w, 858w, 750w, 675w cm-1 1H NMR (acetone-d6): δ 9.96
.
(4H, Har), 7.76 (4H, Har), 8.14 (4H, Har), 4.87 (q, 8H, CF3CH2O). UV/
vis (CH2Cl2): λmax 695.5, 627.0, 344.5, 280.0, 236.5 nm. MS (FD):
m/z 968.1. Anal. Calcd for C40H20F12N8O5Ti: C, 49.61; H, 2.08; N,
11.57; F, 23.54. Found: C, 50.82; H, 2.94; N, 10.26; F, 24.07.
1,2-Dibromo-4,5-bis(2,2,2-trifluoroethyoxy)benzene (2c). 4,5-
Dibromocatechol (1c) (82 mmol, 22 g), 2,2,2-trifluoroethyl tosylate
(197 mmol, 50 g), and anhydrous K2CO3 (197 mmol, 27.2 g) were
dissolved in anhydrous DMF (150 mL) and refluxed at 120 °C for 24
h under nitrogen. After cooling, the mixture was filtered, poured into
water (600 mL), and extracted with CH2Cl2. The organic phase was
washed with water and dried over MgSO4. After evaporation of the
solvent, the product was separated by column cromatography (silica
gel, toluene/Et2O (9:1), Rf ) 0.75). Yield: 19 g (54%), waxy solid.
IR (NaCl): 663m, 804w, 835w, 862m, 883m, 908w, 966s, 1057s,
1163s, 1254s, 1285s, 1360m, 1408w, 1458m, 1487s, 1589w, 2961w
These results set trends for future research. Dense films with
closely packed phthalocyanine units have to be formulated since,
in these films, charge transport is favored over oxygen transport.
Thus, high photoconductivity and photostability coincide. An
elevated HOMO level of the phthalocyanines seems to be helpful
in the preparation of such films, but further efforts have to be
made in the investigation of the deposition parameters.
Experimental Section
Absorbances were determined using a Perkin-Elmer Lambda 2
spectrometer. The syntheses of compounds 3a,20 7a,b,21 9,24 11,25 13,23
and 4,5-dibromocatechol38 (1c) are described in the literature. 2,3-
Dicyanohydroquinone (5c) is commercially available. In general, the
purification of the titanium oxo complexes by column chromatography
was carried out under strict exclusion of light.
cm-1
.
1H NMR (CDCl3): δ 7.22 (H-2, s, 2H), 4.35 (H-1, q, 4H, 3JHF
1
) 8.0 Hz). 13C NMR (CDCl3): δ 147.66 (C-a), 122.92 (C-2, JCF
)
278 Hz), 122.13 (C-b), 118.41 (C-c), 67.88 (C-1, 2JCF ) 36 Hz). MS
(EI): m/z 431.8 (M+). Anal. Calcd for C10H6F6O2Br2: C, 27.81; H,
1.40; Br, 37.00. Found: C, 30.03; H, 1.58; Br, 35.30.
4,5-Dicyano-1,2-bis(2,2,2-trifluoroethoxy)benzene (3c). 1,2-Di-
bromo-4,5-bis(2,2,2-trifluoroethyoxy)benzene (2c) (22 mmol, 9.5 g) and
CuCN (66 mmol, 5.9 g) were dissolved in anhydrous DMF (100 mL)
and refluxed for 8 h at 150 °C under nitrogen. After cooling, the
mixture was poured into concentrated aqueous ammonia (500 mL),
and air was bubbled through the solution for 24 h. The precipitate
was filtered off and washed with aqueous ammonia until the filtrate
was colorless and finally with water. After drying, the product was
extracted in a Soxhlet apparatus with toluene for 24 h. The solvent
was evaporated and the crude product was further purified by column
chromatography (silica gel, toluene/ether (15:1), Rf ) 0.3) and
recrystallization from methanol. Yield: 3.0 g (42%), white crystals,
mp 119 °C. IR (KBr): 663m, 891m, 972s, 1038m, 1103m, 1169s,
1217m, 1231m, 1271s, 1298s, 1362m, 1410m, 1454m, 1529s, 1582m,
2,9,16,23-Tetrakis(trifluoromethyl)phthalocyaninatotitanium-
(IV) Oxide (4a). A mixture of 3a (1.5 mmol) and urea (10 mg) was
heated in 1-octanol (3 mL) to 190 °C, and then titanium(IV) butoxide
(174 mg, 0.51 mmol) was added while a strong stream of nitrogen
was passed through the solution. The mixture was refluxed for 6 h
under a slow continuous stream of nitrogen. After cooling, the mixture
was poured into H2O/MeOH/EtOH (1:1:1). The solid was centrifuged
and washed with EtOH to give the crude product, which was purified
by dissolving in pure acetone and centrifuging to separate the rest of
the titanium(IV) oxide. This procedure was repeated, and the product
was precipitated with hexane. The remainder of the dinitrile was
extracted with dichloromethane in a Soxhlet apparatus. The pure
product was dried under vacuum at 100 °C overnight. Yield: 102 mg
(32%), dark blue powder. IR (KBr): 1622w, 1472w, 1315w, 1265m,
1603m, 2239m, 2959w, 3074m cm--1
.
1H NMR (acetone-d6): δ 7.87
1171m, 1126s, 1062m, 1042m, 1008w, 906w, 841w, 746w cm-1 13C
.
3
(H-b, s, 2H), 4.96 (H-1, q, 4H, JHF ) 8.3 Hz). 13C NMR (acetone-
CP MAS NMR: δ 144.07, 132.46, 121.92. UV/vis (chlorobenzene):
λmax 689.0, 621.0 nm. MS (FAB): m/z 847,9. Anal. Calcd for
C36H12F12N8OTi: C, 50.94; H, 1.43; N, 13.21; F, 26.88. Found: C,
50.67; H, 1.88; N, 12.80; F, 27.15.
1,2-Dicyano-4-(2,2,2-trifluoroethoxy)benzene (3b). 1,2-Dicyano-
4-nitrobenzene (2b) (1.7 g, 10 mmol) was dissolved in anhydrous DMF
(20 mL). Anhydrous potassium carbonate (30 mmol, 4.1 g) and 2,2,2-
trifluoroethanol (30 mmol, 3.0 g) were then added. The mixture was
stirred for about 20 h at room temperature and then finally poured into
water (150 mL). The precipitate was suction filtered, washed with water
and dried under vacuum. Yield: 2.1 g (93%), white solid, mp 82-83
°C. IR (KBr): 663w, 719w, 742w, 829m, 856w, 893m, 935w, 957w,
d6): 151.53 (C-a), 124.33 (C-2, 1JCF ) 277 Hz), 120.19 (C-b), 116.04
2
(C-d), 111.09 (C-c), 67.28 (C-1, JCF ) 36 Hz). MS (EI): m/z 324.1
(M+). Anal. Calcd for C12H6F6N2O2: C, 44.46; H, 1.87; N, 8.64.
Found: C, 44.58; H, 1.99; N, 8.55.
2,3,9,10,16,17,23,24-Octakis(2,2,2-trifluoroethoxy)phthalocyani-
natotitanium(IV) Oxide (4c). A mixture of 1,2-dicyano-4,5-bis(2,2,2-
trifluoroethoxy)benzene (2c) (1.5 mmol) and DBU (0.5 mL) was heated
in 1-pentanol (3 mL) to 140 °C and then titanium(IV) butoxide (0.51
mmol, 174 mg) was added while a strong stream of nitrogen was
bubbled through the solution. The mixture was refluxed for 6 h under
a slow continuous stream of nitrogen. After cooling, the mixture was
poured into H2O/MeOH (1:1). The solid was centrifuged, washed with
EtOH, dissolved in acetone, and suction filtered through a sintered glas
(38) Kohn, M. J. Am. Chem. Soc. 1951, 73, 480.

11672 J. Am. Chem. Soc., Vol. 120, No. 45, 1998
Winter et al.
funnel (3 Å) to separate the rest of the titanium(IV) oxide. The
remainder of the dinitrile was extracted with CH2Cl2. The solvent was
evaporated in a vacuum and the product dried under vacuum at 80 °C.
Yield: 76 mg (15%), dark blue powder. IR (KBr): 2966w, 1614w,
1587w, 1489s, 1472s, 1400s, 1333m, 1263s, 1169vs, 1080s, 1053m,
7c. Yield: 0.7 g (78%), reaction time 3 d, mp 250 °C. IR (KBr):
3470m, 3339w, 3092m, 2974m, 2764w, 1657s, 1618m, 1547m, 1456s,
1427m, 1298vs, 1254vs, 1165vs, 1130s, 1086s, 972s, 881w, 858w,
833m, 798w, 710w, 652w cm-1 1H NMR (DMSO-d6): δ 4.96 (q,
.
3JHF ) 8 Hz, 4H, -CH2-), 7.36 (s, 2H, HAr). 13C NMR (DMSO-d6):
1
3
1015w, 1003w, 964s, 889m, 858m, 829m, 743m, 660m cm-1
.
13C CP
δ 124.0 (q, JHF ) 278 Hz, CF3), 65.6 (q, JHF ) 33 Hz, CH2), 167.4
(s, Car-O), 147.8 (NCN), 118 (Car), 120 (Car). MS (EI): m/z 342.0
(M+), 322.1 (M+ - F), 302.0 (M+ - 2F), 272.1 (M+ - CF3), 243.0
(M+ - CF3CH2O), 203.1 (M+ - CF3CH2O - 2F), 189.1, 175.1, 161.1,
133.1, 129.1, 105.1, 83.0, 76.1, 63.1, 42.9. Formula: C12H9F6N3O2.
1,4,8,11,15,18,22,25-Octa(pentyl)- and 1,4,8,11,18,22,25-Octa-
(hexyl)phthalocyaninatotitanium(IV) Oxide (8a,b). A mixture of the
diiminoisoindoline 7a or 7b (0.61 mmol), titanium(IV) butoxide (1.5
g, 4.41 mmol), and DBU (0.5 mL) was heated in a sealed ampule under
a nitrogen atmosphere to 180 °C for 6 h. The viscous oil obtained
was cooled, and the phthalocyanine was isolated by column chroma-
tography (silica gel/toluene). The first green fraction was eluted and
the solvent evaporated. To achieve further purification, the product
was precipitated by addition of acetonitrile, centrifuged, and dried in
vacuo at 100 °C.
MAS NMR: δ 150.9-149.2, 144.3-140.9, 131.0, 127.9, 114.3, 103.7,
70.5-65.9 (CH2). UV/vis (acetone-d6): λmax 684.5, 619.0 nm. MS
(FD): m/z 1359.0. Anal. Calcd for C48H24F24N8O9Ti: C, 42.35; H,
1.78; N, 8.24; F, 33.52. Found: C, 39.58; H, 1.95; N, 7.62; F, 37.14.
1,2-Dicyano-3,6-bis(2,2,2-trifluoroethoxy)benzene (6c). NaOMe
(62 mmol, 3.4 g) was dissolved under nitrogen in anhydrous methanol
(50 mL), and 2,3-dicyanohydroquinone (5c) (31 mmol, 5.0 g) was
added. The mixture was stirred for 2 h at room temperature.
Afterward, the solvent was evaporated and the yellow residue dried
under vacuum and dissolved in anhydrous DMF. After addition of
2,2,2-trifluoroethyltosylate (93 mmol, 23.6 g), the reaction mixture was
refluxed for 36 h. The crude product was precipitated with water and
recrystallized from EtOH. Yield: 6.9 g (69%), beige solid, mp 184
°C. IR (KBr): 644m, 689w, 720w, 758w, 839m, 860m, 970s, 1094s,
1169s, 1194s, 1259s, 1292s, 1319m, 1331m, 1425w, 1448m, 1502s,
8a. Yield: 49 mg (28%), greenish black powder. IR (KBr):
3078vw, 3042vw, 3020vw, 2955vs, 2926vs, 2856s, 1601w, 1574vw,
1502w, 1479vw, 1466w, 1377w, 1319s, 1238vw, 1169m, 1090m,
1070m, 1001vw, 972w, 903vw, 852vw, 816vw, 760vw, 743w, 681w
1583w, 2232s, 2961w, 3061w, 3090w cm-1
.
1H NMR (acetone-d6):
3
δ 4.96 (q, JHF ) 8.4 Hz, 4H, H-1), 7.81 (s, 2H, H-a). 13C NMR
2
(acetone-d6): δ 67.50 (q, JCF ) 36 Hz, C-1), 106.63 (C-c), 113.00
(C-d), 121.33 (C-a), 124.27 (q, 1JCF ) 277 Hz, C-2), 155.23 (C-b). 19
F
cm-1 1H NMR (C6D6): δ 0.95 (t, J ) 7.1 Hz, 24H, CH3), 1.38-1.52
.
NMR (acetone-d6): δ -75.1 (t, 3JFH ) 8 Hz). MS (EI): m/z (relative
intensity) 324.0 (80) [M+], 255.0 (10), 241.0 (100), 159.0 (90), 83.0
(100). Anal. Calcd for C12H6F6N2O2: C, 44.46; H, 1.87; N, 8.64.
Found: C, 44.51; H, 2.11; N, 8.62.
(m, 16H, δ-CH2), 1.70-1.81 (m, 16H, γ-CH2), 2.18-2.35 (m, 16H,
â-CH2), 4.59-4.85 (m, 16H, R-CH2), 7.89 (s, 8H, HAr). 13C NMR
(C6D6): δ 14.38 (CH3), 23.43 (δ-CH2), 30.63, 32.14, 33.26 (R,â,γ-
CH2), 131.40 (C-1), 134.95 (C-3), 139.62 (C-2), 152.48 (C-4). UV/
vis (toluene): λmax 730.5, 696.0 (sh), 655.5, 359.0, 315.5 (sh) nm. MS
(FD): m/z 1136.9. Anal. Calcd for C72H96N8OTi: C, 76.03; H, 8.51;
N, 9.85. Found: C, 76.27; H, 8.64; N, 10.08.
4,7-Di(pentyl)- (7a), 4,7-Di(hexyl)- (7b), and 4,7-Di(2,2,2-trifluo-
roethoxy)-1,3-dihydro-1,3-diiminoisoindoline (7c). Ammonia was
bubbled vigorously through a solution of 3,6-di(pentyl)phthalodinitrile
(6a) (3.7 mmol, 993 mg), 3,6-bis(hexyl)phthalodinitrile (6b) (6.8 mmol,
2.02 g), or 3,6-bis(2,2,2-trifluoroethoxy)phthalodinitrile (6c) (2.6 mmol,
900 mg) and NaOMe (45 mg) in anhydrous methanol (75 mL) for 2 h
at room temperature. The stream of ammonia was then reduced to a
slight current, while the solution was heated to 60 °C. The reaction
was monitored by TLC (silica gel/CH2Cl2) and terminated after most
of the phthalodinitriles had reacted. On cooling, the diiminoisoindolines
7a-c precipitated overnight at ca. -20 °C. The crude products were
suction filtered, washed with ice cold MeOH (30 mL), and air-dried.
To remove unreacted phthalodinitriles, the products were stirred in
hexane, filtered, and dried in vacuo at 40 °C. They can be used for
phthalocyanine formation without further purification.
8b. Yield: 84 mg (44%), greenish black powder. IR (KBr):
3076vw, 3040vw, 3017vw, 2955s, 2926vs, 2870m, 2854s, 1601vw,
1574vw, 1502w, 1466w, 1423vw, 1377vw, 1323m, 1304m, 1231vw,
1094w, 1072m, 1020vw, 972m, 906vw, 825w, 760vw, 746w, 723vw,
683vw cm-1 1H NMR (C6D6): δ 0.90 (t, J ) 6.9 Hz, 24H, CH3),
.
1.28-1.49 (m, 32H, δ,ꢀ-CH2), 1.73-1.84 (m, 16H, γ-CH2), 2.25-
2.36 (m, 16H, â-CH2), 4.58-4.86 (m, 16H, R-CH2), 7.91 (s, 8H, HAr).
13C NMR (C6D6): δ 14.33 (CH3), 23.13 (ꢀ-CH2), 29.66, 30.96, 32.59,
33.35 (R,â,γ,δ-CH2), 131.49 (C-1), 134.95 (C-3), 139.69 (C-2), 152.50
(C-4). UV/vis (toluene): λmax 730.5, 696.0 (sh), 656.0, 409 (sh), 362.0,
316.0 (sh) nm. MS (FD): m/z 1249.0. Anal. Calcd for C80H112N8-
OTi: C, 76.89; H, 9.03; N, 8.97. Found: C, 77.96; H, 9.23; N, 9.20.
1,4,8,11,15,18,22,25-Octa(2,2,2-trifluoroethoxy)phthalocyani-
natotitanium(IV) Oxide (8c). A mixture of 7c (0.64 mmol, 200 mg)
and naphthalene (0.7 mmol, 90 mg) was dissolved in anhydrous
1-chloronaphthalene (2 mL) with TiCl4 (0.18 mmol, 0.02 mL). The
mixture was heated in a sealed ampule under a nitrogen atmosphere to
190 °C for 24 h. After cooling, the crude product was centrifuged by
washing with MeOH/H2O (1:1). The resulting viscous oil was treated
with hexane to give a green powder which was purified by column
chromatography (silica gel, hexane/acetone (1:1)). The green fraction
was collected and evaporated under vacuum to give a green residue
which was washed again with hexane and dried in vacuo at 85 °C.
Yield: 45 mg (21%), greenish powder. IR (KBr): 1728, 1597, 1502,
1454, 1404, 1290, 1244, 1211, 1163, 1067, 1001, 964, 910, 833, 663
7a. Yield: 377 mg (36%), reaction time 5 d, mp 135-136 °C dec.
IR (KBr): 3454w, 3206m, 2957s, 2932vw, 2856m, 2723vw, 1678m,
1643w, 1620s, 1610s, 1537vs, 1441s, 1339m, 1317m, 1171vw, 1136s,
1053vw, 932vw, 822vw, 733vw, 654vw cm-1 1H NMR (C6D6): δ
.
0.86 (t, J ) 6.6 Hz, 6H, CH3), 1.24-1.32 (m, 8H, γ, δ-CH2), 1.51-
1.62 (m, 4H, â-CH2), 2.88 (broad singlet, NH), 3.05-3.14 (m, 4H,
R-CH2), 7.24 (s, 2H, HAr), 7.92, 8.53, 9.29 (broad singlets, NH). 13C
NMR (C6D6): δ 14.10 (CH3), 22.20 (δ-CH2), 30.19, 30.64, 31.39
(R,â,γ-CH2), 132.42 (C-1), 135.43 (C-3), 138.60 (C-2), 158.29, 167.68,
170.46 (C-4). MS (EI): m/z 285.2 (M+), 256.2 (M+ - C2H5), 242.2
(M+ - C3H7), 229.2, 184.1 (M+ - CH3 - C6H13), 170.0 (M+ - C2H5
- C6H13), 155.0, 114.9 (M+ - 2C6H13), 77.0. Anal. Calcd for
C18H27N3: 75.74; H, 9.53; N, 14.72. Found C, 76.27; H, 9.47; N, 14.45.
7b. Yield: 1.54 g (72%), reaction time 7 d, mp 116-117 °C dec.
IR (KBr): 3456w, 3368vw, 3207w, 2955s, 2930vs, 2870m, 2854s,
1676m, 1620s, 1610s, 1537vs, 1441s, 1377vw, 1339m, 1315m, 1171vw,
cm-1 1H NMR (THF-d8): δ 8.20 (s, 8H, Har), 5.6 (q, 3JHF ) 8.7 Hz,
.
32H, CF3CH2O-). 13C NMR (acetone-d6): δ 152.2 (Car-O), 149.7
1
(NCN), 129.0 (q, JCF ) 123 Hz, CF3), 127.6 (Car), 123.2 (Car-H),
2
70.1 (q, JCF ) 35 Hz, O-CH2-). 19F NMR (acetone-d6): δ -74.4
1136s, 1059w, 922vw, 822vw, 725vw, 652vw cm-1
.
1H NMR
(t, 3JHF ) 8.6 Hz, 24F, CF3-CH2-O). UV/vis (CH2Cl2): λmax 745.0,
668.0 (sh), 354.5 (sh), 327.0 nm. MS (FD): m/z 1359.8. Anal. Calcd
for C48H24F24N8O9Ti: C, 42.35; H, 1.78; N, 8.24; F, 33.52. Found:
C, 43.77; H 2.11; N, 7.76; F, 34.28.
(C6D6): δ 0.83 (t, J ) 6.9 Hz, 6H, CH3), 1.20-1.31 (m, 8H, γ,δ,ꢀ-
CH2), 1.49-1.60 (m, 4H, â-CH2), 2.76 (broad singlet, NH), 2.94-
3.13 (m, 4H, R-CH2), 7.23 (s, 2H, HAr), 7.95, 8.50, 9.29 (broad singlets,
NH). 13C NMR (C6D6): δ 14.03 (CH3), 22.17 (ꢀ-CH2), 28.63, 30.39,
30.83, 31.28 (R,â,γ,δ-CH2), 132.29 (C-1), 134.44 (C-3), 146.01 (C-
4). MS (EI): m/z 313.0 (M+), 295.2 (M+ - NH3), 281.2 (M+ - NH3
- CH3), 270.2 (M+ - C3H7), 256.2 (M+ - C4H9), 243.0 (M+ - C5H11),
228.0 (M+ - C6H13), 183.8 (M+ - C3H7 - C6H13), 170.0 (M+ - C4H9
- C6H13), 155.0 (M+ - NH3 - C4H9 - C6H13), 42.9 (C3H7+).
Formula: C20H31N3.
3,12,21,30-Tetra(tert-butyl)-2,3-naphthalocyaninatotitanium (IV)
Oxide (10). A mixture of 2,3-dicyano-6-tert-butylnaphthalene (9) (0.85
mmol, 200 mg), titanium(IV) butoxide (1.7 mmol), and DBU (0.5 mL)
was heated in a sealed ampule under nitrogen to 195 °C for 6 h. The
oily product was precipitated with MeOH/H2O (1:1) and purified by
column chromatography, CHCl3/CH2Cl2 (2:1). The pure green powder

Classification of Substituted Pc- and NcTiO’s
J. Am. Chem. Soc., Vol. 120, No. 45, 1998 11673
was washed with methanol and dried under vacuum at 100 °C. Yield:
87 mg (41%), dark green powder. IR (KBr): 2955m, 2905w, 1367m,
1356s, 1317m, 1271w, 1258m, 1076vs, 974m, 903m, 891w, 810w,
(0.5 mL) was heated in a sealed ampule under nitrogen to 195 °C for
6 h. The crude product was precipitated with MeOH/H2O (1:1) and
purified by column cromatography, CHCl3. The pure dark blue powder
was washed with methanol and dried under vacuum at 150 °C. Yield:
110 mg (76%), dark blue powder. IR (KBr): 2959s, 2907m, 2870m,
1587m, 1477s, 1460s, 1393s, 1366s, 1261m, 1196m, 1126m, 1107m,
744w, 725w cm-1 1H NMR (CDCl3): δ 9.3-9.0 (m, 2H, Har), 8.6-
.
8.0 (m, 3H) 1.9 (s, 9H, tert-butyl). 13C NMR (CDCl3): δ 150.4,
134.5, 132.6, 130.1, 126.7, 125.2, 123.6, 123.0, 35.5 (CH3C-), 31.7
(CH3C-). UV/vis (THF): λmax ) 801.5, 714.5, 358.0, 349.5 nm. MS
(FAB): m/z 1000.2. Anal. Calcd for C64H56N8OTi: C, 76.77; H, 5.64;
N, 11.20. Found: C, 76.19; H, 5.96; N, 10.82.
1080m, 974m, 901w, 843m cm-1 13C CP MAS NMR: δ 146.7 (NCN),
.
129.0 (Car), 122.9 (Car), 33.0 (CH3C). UV/vis (THF): λmax 799.0, 712.5,
592.0, 358.5, 334.0, 247.0 nm. MS (FAB): m/z 1000.3. Anal. Calcd
for C64H56N8OTi: C, 76.77; H, 5.64; N, 11.20. Found: C, 75.19; H,
5.98; N, 10.62.
1,2-Naphthalocyaninatotitanium(IV) Oxide (12). A mixture of
1,2-dicyanonaphthalene (11) (1.1 mmol, 200 mg), titanium(IV) butoxide
(100 mg), urea (10 mg), and DBU (0.5 mL) was heated in 1-octanol
(2 mL) in a sealed ampule under nitrogen to 195 °C for 1.5 h. After
cooling, the mixture was precipitated with H2O/MeOH (1:1) and
extracted overnight with MeOH. Yield: 177 mg (78%), dark green
powder. IR (KBr): 1620w, 1584m, 1391s, 1356m, 1205m, 1155w,
1125m, 1081vs, 964s, 870w, 822s, 758s, 729s. 13C CP MAS NMR:
Acknowledgment. We are grateful to the Deutsche Fors-
chungsgemeinschaft DFG for financial support of this research.
Special thanks are expressed to the group of Prof. Dr. Bertagnolli
and his co-worker Achim Weber for EXAFS measurements of
II.
δ 137.2, 137.1, 134.4, 131.4, 130.9, 130.0, 128.6 cm-1
. UV/vis
(1-chlornaphthalene): λmax 710.0, 638.0, 368.0 nm. MS (FAB): m/z
776.2. Anal. Calcd for C48H24N8OTi C, 74.23; H, 3.12; N, 14.43.
Found: C, 75.92; H, 3.91; N, 13.64.
2,11,20,29-Tetra(tert-butyl)-1,2-naphthalocyaninatotitanium-
(IV) Oxide (14). A mixture of 1,2-dicyano-7-tert-butylnaphthalene
(13) (0.85 mmol, 200 mg), titanium(IV) butoxide(1.7 mmol), and DBU
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