ABSTRACT This study investigates the stability of chalcone isomers namely trans-3-(i,j-dichlorophenyl)-1-(4-methoxyphenyl)prop-2-en-1-one, where (i) and (j) represent the position of chlorine atoms on the (B) ring such that i and j =2,3,4,5 and 6, by using DFT(B3LYP)/6-311G(d,p) in the gas phase. The s-cis conformers are more stable than the s-trans. The syn is more stable than anti-syn except in (3,4) isomer. Isomers stability follow the trend (3,5)> (2,4)> (2,5)> (3,4)> (2,6)> (2,3). The energy gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) was following the order (2,6)> (2,3)> (2,4)> (2,5)> (3,4)> (3,5). Frontier molecular orbital properties were found a function of HOMO, LUMO or energy gap. Molecular electrostatic potential explained sites of electrophilic and nucleophilic attack. All the investigated chalcones isomers have higher hyperpolarisability values than urea by at least 20 times with the (2,6) isomer being the highest.

中文翻译：

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对甲氧基二氯查耳酮异构体的 DFT。研究结构、构象、FMO、电荷和 NLO 特性

摘要 本研究调查了查耳酮异构体的稳定性，即反式-3-(i,j-二氯苯基)-1-(4-甲氧基苯基)prop-2-en-1-one，其中 (i) 和 (j) 代表位置通过在气相中使用 DFT(B3LYP)/6-311G(d,p)，在 (B) 环上的氯原子的数目使得 i 和 j = 2,3,4,5 和 6。s-cis 构象异构体比 s-trans 更稳定。除了 (3,4) 异构体外，syn 比 anti-syn 更稳定。异构体稳定性遵循趋势(3,5)>(2,4)>(2,5)>(3,4)>(2,6)>(2,3)。最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO）之间的能隙遵循以下顺序（2,6）>（2,3）>（2,4）>（2,5）>（3 ,4)> (3,5)。发现前沿分子轨道特性是 HOMO、LUMO 或能隙的函数。分子静电势解释了亲电和亲核攻击的位点。所有研究的查耳酮异构体都具有比尿素高至少 20 倍的超极化值，其中 (2,6) 异构体最高。