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Updated: Oct 25, 2026

Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
Alkoxy Substitution Controls Columnar Organization in Quinoxaline Cyclotetrabenzoin Macrocycles
Ashikur Rahman Rabbi1, Sandipan Ghorai1, Asmita Shah2
1Department of Chemistry, University of Houston, 3585 Cullen Blvd., Houston, Texas77204-5003, United States.
Abstract:
Shape-persistent quinoxaline macrocycles were synthesized from cyclotetrabenzil through condensations with substituted phenylenediamines. Variation of peripheral alkoxy substituents systematically modulates supramolecular organization in the solid state. Selected tetraalkoxy macrocycles form ordered soft crystal columnar hexagonal phases, whereas octaalkoxy derivatives exhibit more diverse phase behavior. Notably, a branched 3,7-dimethyloctyl derivative displays a columnar oblique liquid-crystalline phase. Single-crystal structures reveal layered packing governed primarily by weak [C-H···O], [C-H···N], and [C-H···π] interactions. These results demonstrate that macrocycle size and side-chain architecture influence columnar packing and phase behavior in quinoxaline macrocycles, with the branched octaalkoxy derivative uniquely exhibiting a liquid-crystalline mesophase.
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