Synthesis and structural characterization of poly-thiolactones with varied ring sizes and endocyclic functional groups

Abstract

The synthesis and isolation of new thiolactone species containing endocyclic ether, polyether, and lactone groups were designed using the reaction between diacyl chlorides with organometallic tin compounds as a template for controlled thioester bond formation. Thus, eight polythiolactones, including cyclo and spiro compounds with different ring sizes and functional groups were prepared, namely 1-oxa-4,9-dithiacycloundecane-5,8-dione (1a), 1-oxa-4,10-dithiacyclododecane-5,9-dione (1b), 1,4-dioxa-7,12-dithiacyclotetradecane-8,11-dione (2a), 1,4-dioxa-7,13-dithiacyclopentaecane-8,12-dione (2b), 2,15,19,32-tetraoxa-6,11,23,28-tetrathia-spiro[16.16]tritriacontane 3,7,10,14,20,24,27,31-octaone (3a), 2,16,20,34-tetraoxa-6,12,24,30-tetrathia-spiro[17.17]pentatriacontan-3,7,11,15,21,25,29,33-octaone (3b), 9,12,25,28-tetraoxa-6,15,22,31-tetratia-1(1,4),17(1,4)-diphenylcyclodotriacontane-5,16,21,32-tetraone (2c), and 2,17,21,36-tetraoxo-6,13,25,32-tetrathia-8(1,4)27(1,4)-diphenyl-spiro[18-18]heptatriacontane-3,7,12,16,22,26,31,35-octaone (3c). The structural characteristics of the eight closely related derivatives were determined by examining the impact of ring size and functional groups, through single-crystal X-ray diffraction techniques. The crystal packing of these polythiolactones was found to be mainly governed by weak C-H···O hydrogen bonding and van der Waals interactions, resulting in partially overlapping tubular arrangements. Hirshfeld analysis was performed to investigate the crystal packing and intermolecular interactions. The results of this study show the possibility of forming 3D tubular arrangements using polythiolactones with various endocyclic groups, including both flexible and rigid spacers.