Structure and photoluminescent features of di-amide cross-linked alkylene–siloxane hybrids

S. C. Nunes; V. de Zea Bermudez; J. Cybinska; R. A. Sá Ferreira; J. Legendziewicz; L. D. Carlos; M. M. Silva; M. J. Smith; D. Ostrovskii; J. Rocha

doi:10.1039/B505372M

Structure and photoluminescent features of di-amide cross-linked alkylene–siloxane hybrids

S. C. Nunes,^a V. de Zea Bermudez,*^a J. Cybinska,^bc R. A. Sá Ferreira,^b J. Legendziewicz,^c L. D. Carlos,*^b M. M. Silva,^d M. J. Smith,^d D. Ostrovskii^e and J. Rocha^f

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* Corresponding authors

^a Departamento de Química and CQ-VR, Universidade de Trás-os-Montes e Alto Douro, 5000-911 Vila Real, Portugal
E-mail: vbermude@utad.pt
Fax: +351 259 350480
Tel: +351 259 350253

^b Departamento de Física and CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal
E-mail: lcarlos@fis.ua.pt
Fax: +351 234 424965
Tel: +351 234 370946

^c Faculty of Chemistry, University of Wroclaw, 14 F. Joliot-Curie, 50-383 Wroclaw, Poland
E-mail: jl@wchuwr.chem.uni.wroc.pl
Fax: +48 71 3282348
Tel: +48 71 3757300

^d Departamento de Química, Universidade do Minho, Gualtar, 4710-057 Braga, Portugal
E-mail: mjsmith@quimica.uminho.pt
Fax: +351 253 678983
Tel: +351 253 676376

^e Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg, Sweden
E-mail: dostr@fys.chalmers.se
Fax: +46 31 772 317
Tel: +46 31772 8038

^f Departamento de Química and CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal
E-mail: rocha@quimica.ua.pt
Fax: +351 234 370084
Tel: +351 234 370730

Abstract

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 [–(CH₂)Si(OSi)₂(OH)] substructures. Structural unit distances of 4.1 and 4.2 Å and average interparticle distances of 12 and 17 Å 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%.

This article is part of the themed collection: Functional hybrid materials

Journal of Materials Chemistry

Structure and photoluminescent features of di-amide cross-linked alkylene–siloxane hybrids

Abstract

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Structure and photoluminescent features of di-amide cross-linked alkylene–siloxane hybrids

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