Mechanochromic Properties of Boron‐Difluoride Complexes Bearing π‐Expanded Pyridine Ligands: Effects of π‐Conjugated Skeletons and Halogen Atoms
Takeo Nakano, Akifumi Sumida, Kensuke Naka
Abstract
Abstract Halogenated and non‐halogenated boron complexes bearing pyrrole and π‐expanded pyridine structures, such as quinoline (for 1 a‐H , 1 a‐Cl , 1 a‐Br , and 1 a‐I ), isoquinoline (for 1 b‐Br ), and phenanthridine (for 1 c‐Br ), were prepared to investigate their optical properties. Fluorescence studies of the different solid states revealed that the boron complexes 1 a‐H , 1 a‐Cl , and 1 a‐Br exhibit the mechanochromic properties. The present paper also examined the optical properties of other analogs 1 a‐I , 1 b‐Br , and 1 c‐Br both in‐solution and solid state. Moreover, the interrelationship between their emission character, molecule structures, and solid state were studied by X‐ray crystallographic analysis and X‐ray diffraction investigation.