Molecular assembly and photoluminescence of novel rare earth/inorganic/polymeric hybrid materials with functional covalent linkages

Abstract

In the context, organic polymeric precursor, polyethylene glycol (PEG) was firstly modified by inorganic component of 3-(triethoxysilyl)-propyl isocyanate (TEPIC) to form the inorganic/organic polymeric functional bridge precursor. Subsequently, the corresponding organic/inorganic molecular-based hybrids were assembled to behave the structural polymeric ligands with the two components equipped with covalent bonds. The coupling reagent part is a functional ureasils –NHC(=O)–O–group which is applied to coordinate to RE 3+ and further formed Si–O backbones after hydrolysis and polycondensation processes. Furthermore, aromatic carboxylic acids (picolinic acid (HPIC), 2-chlorobenzoic acid (HCBA) and salicylic acid (HSAL)) were used as functional sensitized ligands to coordinate with RE 3+(Eu 3+, Tb 3+ and Dy 3+) and resulting in the quaternary rare earth/inorganic/organic polymeric hybrid materials with chemical bond (covalent bonds of –CO–NH– and Si–O, coordination bond of RE–O–C). Luminescence spectra were utilized to characterize the photophysical properties of the obtained hybrid material and the intramolecular energy transfer process took place within these molecular-based hybrids and characteristic emissions of RE 3+ have been achieved.