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Titolo:
Origin of the broken conjugation in m-phenylene linked conjugated polymers
Autore:
Hong, SY; Kim, DY; Kim, CY; Hoffmann, R;
Indirizzi:
Kosin Univ, Dept Chem, Pusan 606701, South Korea Kosin Univ Pusan South Korea 606701 Dept Chem, Pusan 606701, South Korea Kosin Univ, Inst Nat Sci, Pusan 606701, South Korea Kosin Univ Pusan South Korea 606701 t Nat Sci, Pusan 606701, South Korea Korea Inst Sci & Technol, Polymer Mat Lab, Seoul 130650, South Korea KoreaInst Sci & Technol Seoul South Korea 130650 ul 130650, South Korea Cornell Univ, Dept Chem & Chem Biol, Ithaca, NY 14853 USA Cornell Univ Ithaca NY USA 14853 t Chem & Chem Biol, Ithaca, NY 14853 USA
Titolo Testata:
MACROMOLECULES
fascicolo: 18, volume: 34, anno: 2001,
pagine: 6474 - 6481
SICI:
0024-9297(20010828)34:18<6474:OOTBCI>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
STRUCTURAL PHASE-TRANSITION; LIGHT-EMITTING-DIODES; CRYSTAL-STRUCTURE; ELECTRONIC-STRUCTURES; FIRST-PRINCIPLES; AB-INITIO; POLY(PARA-PHENYLENE VINYLENE); ELECTROLUMINESCENT POLYMERS; ELECTROCHEMICAL PROPERTIES; POLYFLUORENE DERIVATIVES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
87
Recensione:
Indirizzi per estratti:
Indirizzo: Hong, SY Kosin Univ, Dept Chem, Pusan 606701, South Korea Kosin Univ Pusan South Korea 606701 , Pusan 606701, South Korea
Citazione:
S.Y. Hong et al., "Origin of the broken conjugation in m-phenylene linked conjugated polymers", MACROMOLEC, 34(18), 2001, pp. 6474-6481

Abstract

A quantum-chemical study of conformations and electronic structures of poly(m-phenylene) [PMP] and the related polyphenylenes was performed to elucidate the origin of the broken conjugation found in m-phenylene linked conjugated polymers. Potential energy curves of the polymers as a function of both torsion and helical angles were constructed through semiempirical Hartree-Fock band calculations at the Austin model I (AM1) level. It is found thattwo helical conformations of PMP are possible: one with a helical angle (alpha) of 72 degrees and the other with alpha = 144 degrees. The former is identical with the conformation of an oligomer in the solid state, m-deciphenyl structure. Our calculations predict that both helices are more stable by 2.5 kcal/mol per phenyl ring than the anti-coplanar conformation and thatthey exhibit absorption peaks at 5.8 eV. The electronic structure of PMP is, however, not affected significantly by increasing the planarity of a PMPchain but affected by copolymerization with other conjugated units. This implies that localization occurs in the m-phenylene ring itself. We examinedthe electronic structures of PMP and the related copolymers and found thatthe weak conjugation along the m-phenylene linked conjugated backbone is related to the inherent nodal nature of the frontier molecular orbitals of the unit even in the planar conformation.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 25/11/20 alle ore 01:32:05