Lizarraga Emilio, Gil Diego M, Echeverría Gustavo A, Piro Oscar E, Catalán César A N, Ben Altabef Aída
INQUINOA, CONICET, Instituto de Química Física, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Lorenzo 456, T4000CAN Tucumán, Argentina.
Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata and Institute IFLP (CONICET, CCT-La Plata), C.C. 67, 1900 La Plata, Argentina.
Spectrochim Acta A Mol Biomol Spectrosc. 2014 Jun 5;127:74-84. doi: 10.1016/j.saa.2014.02.035. Epub 2014 Feb 24.
The 6-acetyl-2,2-dimethyl-chromane compound was synthesized and characterized by IR, Raman, UV-Visible and (1)H NMR spectroscopies. Its solid state structure was determined by X-ray diffraction methods. The substance crystallizes in the triclinic P-1 space group with a=5.9622(5) Å, b=10.342(1) Å, c=10.464(1) Å, α=63.81(1)°, β=81.923(9)°, γ=82.645(9)°, and Z=2 molecules per unit cell. Due to extended π-bonding delocalization a substantial skeletal fragment of the molecule is planar. The vibrational modes were calculated at B3LYP/6-31G(d,p) level and all of them assigned in the IR and Raman spectra. The DFT calculated (1)H NMR spectrum (chemical shifts) were in good agreement with the experimental data. The electronic (UV-Visible) spectrum was calculated using TD-DFT method in gas phase and it was correlated with the experimental data. The assignment and analysis of the frontier HOMO and LUMO orbitals indicate that the absorption bands are mainly originated from π→π(*) transitions. According to DSC measurements the substance presents a melting point of 93°C and decomposes at temperatures higher than 196°C.
合成了6-乙酰基-2,2-二甲基色满化合物，并通过红外光谱、拉曼光谱、紫外可见光谱和¹H核磁共振光谱对其进行了表征。通过X射线衍射方法确定了其固态结构。该物质结晶于三斜晶系的P-1空间群，a = 5.9622(5) Å，b = 10.342(1) Å，c = 10.464(1) Å，α = 63.81(1)°，β = 81.923(9)°，γ = 82.645(9)°，每个晶胞中有Z = 2个分子。由于π键的离域扩展，分子的一个重要骨架片段是平面的。在B3LYP/6-31G(d,p)水平上计算了振动模式，并在红外光谱和拉曼光谱中对所有振动模式进行了归属。密度泛函理论计算的¹H核磁共振光谱（化学位移）与实验数据吻合良好。在气相中使用TD-DFT方法计算了电子（紫外可见）光谱，并将其与实验数据进行了关联。对前沿HOMO和LUMO轨道的归属和分析表明，吸收带主要源于π→π(*)跃迁。根据差示扫描量热法测量，该物质的熔点为93°C，在高于196°C的温度下分解。
