Generalized Mulliken−Hush Analysis of Electronic Coupling Interactions in Compressed π-Stacked Porphyrin−Bridge−Quinone Systems

• Published in: Journal of the American Chemical Society Vol. 127; no. 32; pp. 11303 - 11310
• Main Authors: Zheng, Jieru, Kang, Youn K, Therien, Michael J, Beratan, David N
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 17.08.2005
• Subjects: Atomic and molecular physics; Benzoquinones - chemistry; Calculations and mathematical techniques in atomic and molecular physics (excluding electron correlation calculations); Electron Transport; Electronic structure of atoms, molecules and their ions: theory; Exact sciences and technology; Molecular Structure; Physics; Porphyrins - chemistry; Semi-empirical and empirical calculations (differential overlap, hückel, ppp methods, etc.); Statistical model calculations (including Thomas-Fermi and Thomas-Fermi-Dirac models); Molecular packing; Frontier orbital; Nitrogen heterocycle; Benzoquinone derivatives; Theoretical study; Electron transfer; Configuration interaction; Electronic structure; Molecular orbital method; Electronic transition; INDO S method; Donor acceptor interaction; Porphyrin derivatives; Organic compounds
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja050984y

Donor−acceptor interactions were investigated in a series of unusually rigid, cofacially compressed π-stacked porphyrin−bridge−quinone systems. The two-state generalized Mulliken−Hush (GMH) approach was used to compute the coupling matrix elements. The theoretical coupling values evaluated with the GMH method were obtained from configuration interaction calculations using the INDO/S method. The results of this analysis are consistent with the comparatively soft distance dependences observed for both the charge separation and charge recombination reactions. Theoretical studies of model structures indicate that the phenyl units dominate the mediation of the donor−acceptor coupling and that the relatively weak exponential decay of rate with distance arises from the compression of this π-electron stack.