Multi-functional supramolecular building blocks with hydroxy piperidino groups: new opportunities for developing nonlinear optical ionic crystals. Issue 31 (6th July 2016)

• Record Type: Journal Article
• Authors: Lee, Kang-Hyun; Lee, Seung-Heon; Yun, Hoseop; Jazbinsek, Mojca; Kim, Jun Wan; Rotermund, Fabian; Kwon, O-Pil
• Is Part Of: CrystEngComm. Volume 18:Issue 31(2016)
• Page Start: 5832
• Page End: 5841
• Publication Date: 2016-07-06
• Subjects: Crystals -- Periodicals; Crystal growth -- Periodicals; Crystallography -- Periodicals; Cristaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Cristallographie -- Périodiques; 548
• DOI: 10.1039/c6ce00401f
• Languages: English
• ISSNs: 1466-8033

Abstract

Abstract : Organic ionic crystals with multi-functional supramolecular building blocks exhibit a non-centrosymmetric crystal structure with a large nonlinear optical response. Abstract : We report on multi-functional supramolecular building blocks for obtaining a non-centrosymmetric crystal structure, which is the essential requirement for achieving a macroscopic second-order nonlinear optical activity. The supramolecular building blocks PM (piperidin-4-ylmethanol) and PO (piperidin-4-ol) consist of a piperidino group acting as a strong electron-donating group and a hydroxyl group acting as a strong hydrogen-bonding group, which also may act as a 'site-isolation' group. The quinolinium crystals PMQ-T and POQ-T that introduce PM and PO blocks, respectively, exhibit a non-centrosymmetric crystal structure with nonlinear optical activity, while analogous quinolinium DAQ-T crystal with the widely used N, N -dimethylamino (DA) group exhibits a centrosymmetric crystal structure without nonlinear optical activity. Compared to the DAQ-T crystal, the PMQ-T and POQ-T crystals exhibit a lower tendency to form a hydrate phase in the crystalline state. The PMQ-T crystal exhibits a higher molecular optical nonlinearity in the crystalline state than the DAQ-T crystal, which is attributed to the 'site-isolation' effect resulting from the bulky PM block. In addition, the PMQ-T crystal exhibits large macroscopic optical nonlinearities with more than 3 times higher off-diagonal effective hyperpolarizability than that of benchmark stilbazolium crystals. Therefore, multi-functional supramolecular building blocks PM and PO can give new opportunities for developing non-centrosymmetric ionic crystals for nonlinear optical applications.