ABSTRACT
This work presents a Raman based approach for the rapid identification of the molecular conformation in a series of new 2,3-thienoimide capped quaterthiophenes, whose crystal structures were determined by synchrotron radiation X-ray powder diffraction. These systems display two conformational polymorphs, known as forms A and B, as a result of the anti-anti-anti and syn-anti-syn arrangements of the quaterthiophene cores. In a micro-Raman and computational study, the spectroscopic differences between the conformers were detected and proved to be suitable markers for polymorph identification. Thus, the synergic employment of diffraction and Raman spectroscopy techniques yields a full and reliable characterization of 2,3-thienoimide capped quaterthiophene compounds in their solid state.
ABSTRACT
Three copper(i) complexes have been obtained by the reaction of CuI with 3-picolylamine in acetonitrile solution and characterized by X-ray powder diffraction, both from synchrotron and laboratory radiation. Photophysical investigations in the solid state revealed highly efficient thermally-activated delayed fluorescence (TADF) with photoluminescence quantum yields (PLQYs) up to 18%. Notably, the complex [Cu2I2(3pica)]∞ displays a strong luminescence thermochromism due to the presence of both 1,3(X + M)LCT excited states and a lower-lying cluster-centered (3CC) one, leading to multiple emission at room temperature; as a result, a white luminescence is achieved with a PLQY of 4.5%.
ABSTRACT
Solid [CuI(piperazine)0.5]∞, characterized by a structure with an infinite double chain of CuI, presents an unexpected dual luminescence. The short copper-copper distances allow the existence of both cluster-centered and 1-D delocalized electronic transitions, as emerged from theoretical calculations. Beyond the more common cluster-centered emission a higher energy band, which differs in lifetime and in temperature dependence, is observed.
