Elucidation of crystal colour change mechanism by crystalline state phase transition and proton transfer

2015 Fiscal Year Final Research Report

• Project/Area Number: 25410005
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Physical chemistry
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: UEKUSA Hidehiro 東京工業大学, 理工学研究科, 准教授 (60242260)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 有機結晶 / Ｘ線結晶構造解析 / ベイポクロミズム / 粉末結晶解析 / 単結晶構造解析 / 脱水転移 / 水和転移

Outline of Final Research Achievements

A wide range of screening of vapochromic organic crystals, a series of quinolone and new-quinolone antibiotic drugs were found to show vapochromic feature. Pipemidic acid trihydrate crystal showed dehydration phase transition by acetonitrile vapor, and back to be hydrate by humidity application. During this transition, the crystal color turned from colorless to yellow as the result of vapochromism. The crystal structure of the pipemidic acid anhydrous phase was determined at the first time by utilizing the Structure Determination from Powder diffraction Data technique which was recently developed. From the comparison of the crystal structures between before and after dehydration, molecular position rearrangement in the crystal induced an intra-molecular proton-transfer which affected the energy level of the molecular orbitals.

Free Research Field

有機結晶化学