The interactions of probes based on substituted pyrene derivatives in polymer matrices; spectral study

Two substituted pyrene derivatives with cholesterol ((3 beta)-cholest-5-en-3-ol) moiety as esters were synthetized. The spectral properties of the mono-substituted derivatives of pyrene as esters with different linkages to cholesterol via carboxy unit (PyCACh1) and methylene carboxy unit (PyMECh2) are compared with the mono-substituted pyrene derivatives and the parent pyrene in toluene at low concentration and doped in glassy polymer matrices of polystyrene (PS), poly(methyl methacrylate) (PMMA) and polyvinylchloride (PVC) in the concentration range of 0.002-0.06 mol kg(-1). Fluorescence spectroscopy of the pyrene derivatives in polymer matrices reveals changes in the shape of the fluorescence spectra with increasing concentration. Two limiting cases are observed: (1) a medium or large red shift of the entire fluorescence spectrum or (2) the formation of an emission band in the excimer emission region (approx. 500 nm). These changes are less pronounced in the pyrene-cholesterol esters in the PS matrix due to higher compatibility than in PMMA and PVC matrices. Exploitation of these emissions to estimate the interactions of the components in the polymer matrix is discussed. (C) 2015 Elsevier B.V. All rights reserved.