2011 Fiscal Year Final Research Report

Creation of macroscopic chiral structures through twisting crystal growth and exploration of their functions

Research Project

Project/Area Number	22656158
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Single-year Grants
Research Field	Structural/Functional materials
Research Institution	Keio University
Principal Investigator	IMAI Hiroaki 慶應義塾大学, 理工学部, 教授 (70255595)
Project Period (FY)	2010 – 2011
Keywords	結晶成長 / ねじれ / キラリティ / 有機結晶 / 光学特性 / ゲル
Research Abstract	Twisted growth of various inorganic and organic crystals was investigated by using organic matrix. Oriented assembly of micrometric twisted crystals on a glass substrate was achieved through dipping of an aqueous solution containing of K_2Cr_2O_7 and poly(acrylic acid). The oriented microstructures of K_2Cr_2O_7 exhibited a unique optical property originating from the periodic twisted crystal growth. The crystal morphology of an organic molecule, pyrene, formed in an organic solvent changed from polyhedral shapes into characteristic curving forms, such as sigmoidal and helical architectures, with increasing the concentration of a polymer, polyvinyl pyrrolidone. The curving forms are inferred to be constructed through a twisted assembly of asymmetric units under diffusion-limited conditions. The controlled growth of inorganic and organic crystals using the polymer matrix would provide a novel type of functional materials having macroscopic chirality.