2-(4-Methyl-phen-yl)quinoline-4-carb-oxy-lic acid

A new mixed-valence CuI/CuII three-dimensional coordination polymer constructed with an N,O-donor ligand generated via solvothermal synthesis: structural features and magnetic properties

A new mixed-valence CuI/CuII three-dimensional coordination polymer, poly[[diaquabis[μ4-2-(pyrazin-2-yl)quinoline-4-carboxylato]dicopper(I)copper(II)] bis(tetrafluoridoborate)], {[Cu3(C14H8N3O2)2(H2O)2](BF4)2} n , was synthesized and characterized, with 2-(pyrazin-2-yl)quinoline-4-carboxylic acid being employed as a linker ligand. The ligand was isolated as its hydrochloride salt, 4-carboxy-2-(pyrazin-2-yl)quinolin-1-ium chloride dihydrate, C14H10N3O2 +·Cl−·2H2O. The compounds show luminescence at 550 nm for the ligand and at 565 nm for the polymer at 297 K. The ligand structure was rationalized by means of quantum-chemical calculations, which led to a similar conformation to that determined from X-ray diffraction studies.

Mechanochromic Luminescence of 2,6-Bis(4-biphenyl)isonicotinic Acid via Interconversion of Classical/Frustrated Brönsted Pair

A practicable strategy to a reversible mechanochromic material featuring interconversion of classical/frustrated Brönsted pairs has been established. We report the mechanochromic property of 2,6-bis(4-biphenyl)isonicotinic acid (1), which features a frustrated Brönsted pair in the crystalline form and a classical Brönsted pair after grinding. A large mechanochromic shift was found from 428 to 505 nm. In addition, compound 1 also exhibits acidochromic behavior, which further proves that the formation of an acid-base interaction is responsible for the mechanochromic phenomenon.