(Photo)physical Properties of New Molecular Glasses End-Capped with Thiophene Rings Composed of Diimide and Imine Units

Abstract

New symmetrical arylene bisimide derivatives formed by using electron-donating–electron-accepting systems were synthesized. They consist of a phthalic diimide or naphthalenediimide core and imine linkages and are end-capped with thiophene, bithiophene, and (ethylenedioxy)thiophene units. Moreover, polymers were obtained from a new diamine, N,N′-bis(5-aminonaphthalenyl)naphthalene-1,4,5,8-dicarboximide and 2,5-thiophenedicarboxaldehyde or 2,2′-bithiophene-5,5′-dicarboxaldehyde. The prepared azomethine diimides exhibited glass-forming properties. The obtained compounds emitted blue light with the emission maximum at 470 nm. The value of the absorption coefficient was determined as a function of the photon energy using spectroscopic ellipsometry. All compounds are electrochemically active and undergo reversible electrochemical reduction and irreversible oxidation processes as was found in cyclic voltammetry and differential pulse voltammetry (DPV) studies. They exhibited a low electrochemically (DPV) calculated energy band gap (Eg) from 1.14 to 1.70 eV. The highest occupied molecular orbital and lowest unoccupied molecular orbital levels and Eg were additionally calculated theoretically by density functional theory at the B3LYP/6-31G(d,p) level. The photovoltaic properties of two model compounds as the active layer in organic solar cells in the configuration indium tin oxide/poly(3,4-(ethylenedioxy)thiophene):poly(styrenesulfonate)/active layer/Al under an illumination of 1.3 mW/cm2 were studied. The device comprising poly(3-hexylthiophene) with the compound end-capped with bithiophene rings showed the highest value of Voc (above 1 V). The conversion efficiency of the fabricated solar cell was in the range of 0.69–0.90%.

Comprehensive UV–Vis and EPR spectroelectrochemical characterization of ambipolar azomethinenaphthaldiimides

“…This work is a continuation of our investigations connected with characterization of donor-acceptor type naphthalene diimide derivatives with imine bond in structures (azomethinenaphthaldiimides) [43,44]. In this paper we had focused on the comprehensive spectroelectrochemical analysis.…”

“…The aim of our investigations was to determine the influence of end-capping (donating groups) on the spectroelectrochemical properties of compounds and to study the nature of interactions between the imide and donor group. The basic electrochemical properties of compounds Azndi 1-3 with and Azndi 4 were described in our former papers [43,44]. In this work, the attempt of electrochemical polymerization of Azndi 1-4, which can be treated as monomers, was undertaken.…”

“…In order to facilitate analysis of spectroelectrochemical results, the electrochemical data are given. Moreover, the conditions of measurement are different from those described in [43,44]. All investigated monomers underwent two-step reduction.…”

“…The synthesis, physical properties and basic optical and redox properties of the investigated monomers and polymers were described in the papers published earlier [43,44]. The chemical structures of investigated azomethinenaphthaldiimides (Azndi) are shown in Fig.…”

Optical and electrochemical properties of novel thermally stable Schiff bases bearing naphthalene unit

“…In our research group we have synthesized several new azomethines derivatives consisting also of phthalic and naphthalene diimides units and also thiophene, bithiophene, and pyridine rings [22][23][24][25]. The most of these compounds exhibited a low electrochemical energy band gap being suitable for a variety of applications.…”