Substituent Effects on the Structural Features and Nonlinear Optical Properties of the Organic Alkalide Li+(calix[4]pyrrole)Li

• Published in: Chemphyschem Vol. 14; no. 2; pp. 408 - 416
• Main Authors: Sun, Wei-Ming, Wu, Di, Li, Ying, Li, Zhi-Ru
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 04.02.2013; WILEY‐VCH Verlag; Wiley; Wiley Subscription Services, Inc
• Subjects: Beta; Calixarenes - chemistry; calixpyrrole derivatives; Chemistry; density functional calculations; Exact sciences and technology; General and physical chemistry; lithium; Lithium - chemistry; Molecular Structure; nonlinear optics; Optical Phenomena; Organometallic Compounds - chemistry; Porphyrins - chemistry; Quantum Theory; substituent effects; Substituent effect; Five membered ring; Polarizability; Nitrogen heterocycle; Non linear optics; Lithium; Pyrrole derivatives; density functional calculations; nonlinear optics; Energy; Ionization; Optical properties; Pyrrole; calixpyrrole derivatives; Density functional method; Structure; Orbital
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201200805

The effects of substituents on the structure, character, and nonlinear optical (NLO) properties of the organic alkalide Li+(calix[4]pyrrole)Li− were studied by density functional theory. Natural bond orbital analysis and vertical ionization energies reveal that electron‐donating substituents strengthen the alkalide character of Li+(calix[4]pyrrole)Li− and that they are beneficial for a larger first hyperpolarizability (β0) value. However, electron‐withdrawing substituents have the opposite effect. The dependence of the NLO properties on the number of substituents and their relative position was detected in multisubstituted Li+(calix[4]pyrrole)Li− compounds. For both the amino‐ and methyl‐substituted derivatives, the polarizabilities and the first hyperpolarizabilities increase as more pyrrole β‐H atoms are substituted. Moreover, distribution of the substituents so that they are as far away from each other as possible resulted in an increase in the β0 value. The new knowledge obtained in this study may provide an effective approach to enhance the NLO responses of alkalides by employing pyrrole derivatives as complexants. Polar opposites: Substituent effects on the nonlinear optical properties of the Li+(calix[4]pyrrole)Li− alkalide are investigated by density functional theory. The study reveals that electron‐donating substituents increase the first hyperpolarizability of Li+(calix[4]pyrrole)Li−, whereas electron‐withdrawing substituents have the opposite effect (see picture).