Structure and photoluminescent features of di-amide cross-linked alkylene-siloxane hybrids
Journal article, 2005

Novel amide cross-linked alkylene-siloxane hybrid materials (di-amidosils) synthesized by the sol-gel process have been investigated. Two samples identified by the notation d-A(x) with x = 4 and 8 (where x is the number of methylene groups of the alkylene chain) have been produced as transparent, amorphous, rigid monoliths. The d-A(8) material is thermally stable up to approximately 245°C. In this hybrid the siliceous framework is mainly composed of [-(CH2)Si(OSi)3)] and [-(CH 2)Si(OSi)2(OH)] substructures. Structural unit distances of 4.1 and 4.2 Å and average interparticle distances of 12 and 17 A have been determined for d-A(4) and d-A(8), respectively. In these compounds the alkylene chains are disordered and adopt gauche conformations. While a negligible proportion of the amide linkages remain non-bonded, the great majority of these groups belong to highly disordered strong hydrogen-bonded amide-amide associations. The hybrids introduced are room temperature white light emitters, presenting an intense, broad emission band in the blue/purplish-blue spectral region. The origin of such a band has been ascribed to the convolution of donor-acceptor pair (D-A) recombinations that occur in the NH groups of the amide linkages and in the siliceous nanodomains. The maximum quantum yield value of the d-A(8) di-amidosil is 5.4%.


S. C. Nunes

University of Trás-os-Montes and Alto Douro

V. D. Bermudez

University of Trás-os-Montes and Alto Douro

J. Cybinska

University of Aveiro

University of Wrocław

R. A. S. Ferreira

University of Aveiro

J. Legendziewicz

University of Wrocław

L. D. Carlos

University of Aveiro

M. M. Silva

University of Minho

M. J. Smith

University of Minho

Denis Ostrovskii

Chalmers, Applied Physics

J. Rocha

University of Aveiro

Journal of Materials Chemistry

0959-9428 (ISSN) 1364-5501 (eISSN)

Vol. 15 35-36 3876-3886

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