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The design of fluorescent molecules with structural features for efficient immobilization in polymeric supports or binding matrixes is an active research topic, which aims to create materials with optical and mechanical properties suitable for sensing applications. Herein, we describe the synthesis and characterization of two new fluorescent ligands prepared by a combination of a rosamine platform and an isophthalate receptor using amine and amide linkages. In order to evaluate their potential application as fluorescence sensors, the photophysical properties of the ligands were accessed by UV-Vis and photoluminescence measurements in solution and after immobilization (infiltrated in TiO 2 thin films). Furthermore, molecular and electronic structures of both ligands were rationalized by DFT and TD-DFT calculations. Interesting features were found for the ligand containing an amide bond, which has shown to be less prone to aggregation and has higher emission capacity, being a promising candidate in fluorescence sensor devices. [ABSTRACT FROM AUTHOR]

Abstract We report on a combinatorial optimization procedure applied to heterojunction small molecule organic solar cells made of evaporated copper phthalocyanine (CuPc) and 3,4,9,10-perylenetetracarboxylic bisbenzimidazole (PTCBI). Our strategy consists of depositing both light harvesting compounds as orthogonally arranged wedge-shaped layers to then determine the optimum thicknesses which yield the highest photoconversion efficiency. The device performance is locally assessed by means of light-beam induced current images. A quantitative model of co-locally measured Raman images allows determining the corresponding local thicknesses of the active layers. The spatial correlation of both datasets (i.e. local photocurrent density and active layer film thicknesses) enables the rapid optimization of the photovoltaic system studied employing a single functional device, reducing in approximately 20 times the use of resources and time. Graphical abstract Image 1 Highlights • Combinatorial optimization approach applied to heterojunction organic solar cells. • The active layers are disposed as orthogonal wedges. • Thicknesses are optimized combining Raman spectroscopy and photocurrent mapping. • 20-fold reduction in the use of resources and time employing a single device. [ABSTRACT FROM AUTHOR]

Two donor-acceptor-donor (D–A–D) and two donor-acceptor (D-A) small molecular systems involving alkyl bithiophene and thiophene derivatives as donor blocks and 5,5′- and 5-linked 7,7′-diazaisoindigo (DAIID) as acceptor blocks have been synthesized and investigated with theoretical calculations and photophysical studies. The incorporation of the thiophene groups led to significant changes in the UV–vis absorption spectra and electronic structure of the diazaisoindigo. Bithiophene and thiophene derivatives did not show fluorescence, in contrast to their dibrominated and brominated precursors. This fact was attributed to both a decrease of the radiative rate constant and an increase of the non-radiative deactivation associated to the incorporation of the thiophenyl groups. Additionally, picosecond transient absorption experiments revealed short time decays for the thiophenyl derivatives indicating a faster non-radiative deactivation associated to a rotation of the central double bond of 7,7′-diazaisoindigo in the excited state. [Display omitted] • Diazaisoindigos derivates incorporating thiophenyl groups have been prepared. • Thiophenyl groups do not lead to a significant change of the molecular structure. • Electronic structure of diazaisoindigos is notably altered by thiophenyl moieties. • Thiophenyl groups leads to a decrease of the radiative rate constant. • Picosecond TA experiments revealed shorter time decays for the thiophenyl derivates. [ABSTRACT FROM AUTHOR]