Charge and spin transfer and optical properties in conducting porphyrin compounds

Abstract

Anisotropic materials made from stacked macrocycles have potential applications as organic conductors and nonlinear optical materials. Using self-consistent-field local density theory, we have been exploring the ground and excited state electronic structures of metal substituted tetraazaporphyrins, phthalocyanines, and tetrabenzoporphyrins. The calculated and measured polarized optical absorption peaks are in satisfactory agreement. The theoretical dipole oscillator strengths provide absolute intensities for verification of transition assignments, which are helpful for identifying low-lying states and excitation mechanisms.

Macrocycle-Macrocycle Interactions within One-dimensional Cu Phthalocyanine Chains

“…There are also four types of carbons (C a , C b , C c , C d ) building up the fivefold and sixfold peripheral benzene rings with H atom termination. The orientation of axes is chosen so that N p atoms lie on the x and y axes, while z is perpendicular to the monomer plane, as in our previous works [8][9][10][11][12][13][14][15]. In this setting, b 1g has (x 2 À y 2 ) symmetry and b 2g behaves as (xy) with respect to the center.…”

“…Phthalocyanines have attracted considerable interest both because of their relationship to the biologically important porphyrins and because of their intrinsically interesting spectroscopic [8][9][10][11][12][13][14][15], magnetic [16,17] and electrochemical [18,19] properties. As far as the electrical and magnetic properties are concerned, the conductors based on partially oxidized phthalocyanine metallomacrocycles show a variety of behaviors which are related to the nature of the metallic center as well as to the substituents on the phthalocyanine framework.…”

Electronic structure and optical properties of a tin‐encapsulated nickel porphyrazine compound

“…Thus, the optical spectrum was found lacking the characteristic Soret band, which usually appears at about 30 kcm-' in the metal-porphyrin and porphyrin derivatives. We previously interpreted the polarized optical spectra of MPc's, M = Co, Ni, or Cu [3], using the first-principles local density theory. Here, we extend the analysis to the new case of tin-encapsulated metal porphyrazines.…”

“…Details of the methodology have been given elsewhere [4,5]. Paralleling our previous work on NiPc and related systems [3], and to reduce computational effort, we decided to idealize the system in D4h symmetry. We took the experimental X-ray crystal data and average to a symmetry of D 4 h with all tin atoms lying in the porphyrazine-octathiolate ligand plane [see Fig.…”

“…its charge on S, 20% on C2 connected to S, 12% on Ni 3dzz,yz, 11% on the N1 connected to Ni, and the remainder distributed on other atoms. The calculated HOMO (19e,) -LUMO (20eg) gap, equal to 0.27 eV, is much smaller than that of NiPc (1.35 eV) [3], which has the same structure within the pyrrol ring [see Fig. l(b)].…”