5,11,17,23-Tetrakis[(p-carboxyphenyl)azo]-25,26,27,28-tetrahydroxy Calix[4]arene: Crystal Structure and pH Sensing Properties
✍ Scribed by Leilei Liu; Zhigang Ren; Hongxi Li; Hai Shang; Prof. Dr. Jianping Lang
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 174 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0256-7660
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Treatment of 5,11,17,23‐tetrakis[(p‐carboxyphenyl)azo]‐25,26,27,28‐tetrahydroxy calix[4]arene (2) with HCl in DMF or NaOH in MeOH produced 5,11,17,23‐tetrakis[(p‐carboxyphenyl)azo]‐25,26,27,28‐tetrahydroxycalix[4]‐arene·4DMF (2·4DMF) and 5,11,17,23‐tetrakis[(p‐carboxyphenylsodium)azo]‐25,26,27,28‐tetrahydroxycalix[4]‐ arene (3), respectively, which were characterized by elemental analysis, IR, UV‐vis, ^1^H NMR and ^13^C NMR. An X‐ray analysis of 2·4DMF revealed that its calix[4]arene core adopts a flattened cone conformation in which opposed phenyl groups take parallel or sharply inclined positions. The intra‐ and intermolecular hydrogen‐bonding interactions and the π···π interactions form a 2D hydrogen‐bonded wavelike network. Compound 2 had a unique reversible color change in a wide pH range from 1 to 13.5 and showed interesting pH sensing properties.