A short and efficient route to a broad range of imidazo[1,2-a]pyridines from 2-aminopyridines and acetophenones is achieved by a tandem, one-pot process starting with an Ortoleva-King reaction. Optimal conditions for the first step were established after examining various reaction parameters (solvent, reagent ratios, and temperature). The conditions identified (1st step, neat, 2.3 equiv of 2-aminopyridine, 1.20 equiv of I(2), 4 h, 110 °C; 2nd step, NaOH(aq), 1 h, 100 °C) resulted in the formation of imidazo[1,2-a]pyridines in 40-60% yields. The synthesis is compatible with various functionalities (OH, NMe(2), Br, OMe). Products containing a 2-(2'-hydroxyphenyl) substituent undergo excited state intramolecular proton transfer (ESIPT) in nonpolar and polar-aprotic solvents. Although ESIPT-type emission in nonpolar solvents is weak, the Stokes shifts are very high (11000 cm(-1)). The comparison of the properties of six ESIPT-capable imidazo[1,2-a]pyridines shows the influence of various substituents on emission characteristics. All of them also display strong, solid-state emission in blue-green-yellow region. 2-Aryl-imidazo[1,2-a]pyridines not capable of ESIPT emit in the blue region, displaying high fluorescence quantum yield.

The recently synthesized C18 molecule demonstrates strong electron acceptor properties similar to C60.

We propose a new atomic-charge analysis, termed adjusted charge partitioning (ACP) scheme. To partition the molecular electronic density into atomic components, weighting factors cAr2n-2exp(-αAr) with atomic parameters cA and αA are used. Extensive numerical tests were performed for 540 molecules containing 17 main-group elements H, Li to F, Na to Cl, Br, and I. The estimated dipole moments and atomic charges are compared with the data provided by a large number of alternative atomic-charge schemes including the Mulliken, Löwdin, Hirshfeld, Hirshfeld Iterative, CM5, ESP, NPA, and QTAIM population analyses. These tests show that the resulting atomic charges are insensitive to basis sets used, chemically consistent and accurately reproduce experimental dipole moments.

Photoinduced electron transfer in CPP-based donor–acceptor complexes C60⊂[10]CPP and Li+@C60⊂[10]CPP was studied using DFT/TDDFT. Unusual blue shift of charge separated states for Li+@C60⊂[10]CPP complexes in the polar medium is predicted.