Salts of the scissor-shaped racemic host 1,1′-binaphthyl-2,2′-dicarboxylic acid with amines: structure and thermal stability?

CrystEngComm Pub Date: 2014-02-11 DOI: 10.1039/C3CE42215A

Abstract

The salts formed between racemic 1,1′-binaphthyl-2,2′-dicarboxylic acid (BNDA) and the amines diethylamine (DEA), di-n-butylamine (DBA), cyclohexylamine (CHA) and dicyclohexylamine (DCHA) are reported. Structure 1, (BNDA2?)(2DEA+), and 2a, (BNDA2?)(2DBA+), resulted from slow evaporation of a solution of BNDA in the respective amine. A competition experiment whereby BNDA was dissolved in a mixture of 60% DEA and 40% DBA resulted in a polymorph of 2a, namely 2b. Slow evaporation of dilute solutions of BNDA with CHA and DCHA resulted in a mixed salt solvate 3, (BNDA2?)(3CHA+)(C7NO2H11?)·CHA·H2O, and a salt solvate, 4, (BNDA2?)(2DCHA+)·CH3OH·H2O, respectively. For all the experiments methanol was used as a co-solvent due to BNDA insolubility with the amines. In structure 3 one of the CHA guests reacted with carbon dioxide in the atmosphere to form a carbamate anion, C7NO2H11?. The kinetics of desolvation for salts 1, 2a and 2b were also determined.

Graphical abstract: Salts of the scissor-shaped racemic host 1,1′-binaphthyl-2,2′-dicarboxylic acid with amines: structure and thermal stability
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