Compounds consisting of coplanar π-conjugated B_(3)O_(6)-typed structures:An emerging source of ultraviolet nonlinear optical materials

摘要

Nonlinear optical(NLO)materials as a crucial part of the laser science have attracted increasing attention from researchers because of their wide applications in information storages,modern science and technologies,et al.Based on the anionic group theory,theπ-conjugated 6-membered rings(6-MRs),B_(3)O_(6)-typed structures have key contributions to the superior optical properties ofβ-Ba_(2)B_(2)O_(4)(β-BBO).In recent years,the organic coplanarπ-conjugated B_(3)O_(6)-typed structures have caught researchers'attention due to similar configurations to the(B_(3)O_(6))groups,which are the potential sources for expending the(B_(3)O_(6))groups with outstanding optical properties.Up to know,researchers have obtained many ultraviolet(UV)NLO crystals with excellent properties withπ-conju-gated B_(3)O_(6)-typed groups.Herein,these B_(3)O_(6)-typed groups could be divided into different categories according to the atoms constituting the 6-MRs:(H_(x)C_(3)N_(3)O_(3))^(x-3)(x=0-3)(cyanurate ion),(H_(x)C_(4)N_(2)O_(3))^(x-4)(x=2,3)(barbi-turate ion),(C_(3)H_(7)N_(6))^(+)(melamine ion),(C_(5)H_(6)ON)^(+)(4-hydroxypyridine cation),and(C_(4)H_(6)N_(3))^(+)(2-amino-pyrimidinium cation).In this review,we introduced the research advances of NLO materials withπ-conjugated B_(3)O_(6)-typed groups,and summarized the crystal structures,synthetic methods,optical performances,as well as the relationships between structures and properties.This work provided a clear perspective for understanding the coplanarπ-conjugated B_(3)O_(6)-typed groups with their optical functional properties and promote the searches to develop potential NLO functional crystals.