Nonlinear absorption, refraction, and optical limiting by a series of monoaxially chloro- and aryl-substituted indium(III) phthalocyanines are described. The absorption cross sections and temporal evolution of the low-lying excited states are also reported. A large nonlinear absorption that increased with wavelength between 500 and 590 nm was observed in each material. The nanosecond nonlinear absorption and the optical limiting are shown to be dominated by a strong excited state absorption from an orientationally averaged triplet state. We derive and experimentally confirm the relation between the molecular absorption cross sections and the fluence-dependent nonlinear absorption coefficients. The effective nonlinear refraction on the nanosecond time scale was reduced because the electronic contribution to the nonlinear refractive index was of the opposite sign from the thermal contribution. An optical limiter using the new material, p-(trifluoromethyl)phenylindium(III) tetra-tert-butylphthalocyanine [(t-Bu)4PcIn(p-TMP)], showed a much lower threshold for optical limiting and a much lower transmission at high fluences than previously reported indium phthalocyanine limiters. This improved optical limiting was due both to the larger nonlinear absorption coefficient and to the design of the limiter device. The optical properties of the In phthalocyanine moiety were found to be surprisingly robust to structural changes in the axial position.

No 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 α 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 β films, characterized by weak exciton splitting, are formed from fluorinated phthalocyanines 4a−c as well as from rapidly deposited 2,(3)-substituted phthalocyanines II and the unsubstituted PcTiO (I). These films show enhanced photoconductivity and are generally more stable against photooxidation than type α 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.

The syntheses of highly soluble chloro(naphthalocyaninato)-indium(III) compounds (R 2 ) 4 (R 4 ) 4 NcInCl (5a: R 2 = H, R 4 = tertbutyl; 6a: R 2 = R 4 = tert-butyl; 7a: R 2 = 2-ethylhexyloxy, R 4 = tert-butyl; 8a: R 2 = R 4 = 2-ethylhexyloxy), and their reactions with RЈMgBr [b: RЈ = p-(trifluoromethyl)phenyl; c: RЈ = pentafluorophenyl] producing the axially substituted aryl(naphthalocyaninato)indium(III) compounds 5b, 5c, 6b, 6c, 7b, 7c

No abstract