CAJ | 학술논문

采用密度泛函理论B3LYP/6-31G(d)方法优化计算4种2,4-二甲幕-7-氨基-1,8-萘啶衍生物分子结构,探讨了其分子结构与前线分子轨道、能量的关系.运用含时密度泛函理论(TD-DFT)计算了它们的气相和溶液相电子光谱,研究了溶剂模型和计算方法对理论光谱的影响.计算结果表明,4种萘啶衍生物均含离域π键,HOMO与LUM0能级差ΔE较小,且大小顺序与它们的最大吸收波长实验值变化趋势一致.理论电子光谱证实,1,8-萘啶衍生物的吸收光谱随共轭性增强逐渐红移,最大吸收源自于HOMO→LUMO的π→π*电子跃迁.PCM-B3LYP/6-31+G(d)计算结果与实验值相比,最大吸收波长分别相差2.6,10.3,5.3和6.9 nm,能最相差0.03,0.09,0.04和0.08 eV.因此,在考虑溶剂效应条件下,采用B3LYP/6-31(d)方法优化分子构型和TD-DFT方法获得的电子光谱与实验光谱具有一致性.
채용밀도범함이론B3LYP/6-31G(d)방법우화계산4충2,4-이갑막-7-안기-1,8-내정연생물분자결구,탐토료기분자결구여전선분자궤도、능량적관계.운용함시밀도범함이론(TD-DFT)계산료타문적기상화용액상전자광보,연구료용제모형화계산방법대이론광보적영향.계산결과표명,4충내정연생물균함리역π건,HOMO여LUM0능급차ΔE교소,차대소순서여타문적최대흡수파장실험치변화추세일치.이론전자광보증실,1,8-내정연생물적흡수광보수공액성증강축점홍이,최대흡수원자우HOMO→LUMO적π→π*전자약천.PCM-B3LYP/6-31+G(d)계산결과여실험치상비,최대흡수파장분별상차2.6,10.3,5.3화6.9 nm,능최상차0.03,0.09,0.04화0.08 eV.인차,재고필용제효응조건하,채용B3LYP/6-31(d)방법우화분자구형화TD-DFT방법획득적전자광보여실험광보구유일치성.
The molecular geometries of four 2,4-dimethyl-7-amino-1,8-naphthyridine derivatives were optimized with B3LYP/6-31G(d) method.The energies of their frontier molecular orbitals and the molecular structures were investigated theoretically.The theoretical electronic spectra were calculated with TD-DFT in gas phase,PCM-TD-B3LYP/6-31+G(d) and semiempirical ZINDO in CH_2 Cl2 solution.The influences of solvent model and calculation methods on the electronic absorption spectra were also probed.The calculated results show that delocalized π bonds exist in the four 1,8-naphthyridine derivatives,and their energy gaps (ΔE) between HOMO and LUMO are relatively small.The variation in their ΔE values gives a consistent trend with that of their electronic absorption with λmax.Theoretical spectra achieved prove that their absorptions are red-shifted when the delocalization of π electrons is enhanced or the capability to donate electron by a substituted group is increased.The maximum absorption peaks of the four derivatives originate from π(HOMO)→π* (LUMO) transition.The spectra calculated at the PCMB3LYP/6-31+G(d) level have little difference from experimental results:the differences in wavelength are 2.6,10.3,5.3 and 6.9 nm,whereas those in energies are 0.03,0.09,0.04 and 0.08 eV,respectively.The obtained results suggest that electronic spectra calculated by TD-DFT on the bases of geometries optimized with B3LYP/6-31 (d) are in agreement with experimental ones,and can account for the different spectroscopic properties of the four 1,8-naphthyridine derivatives.