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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Conformational flexibility, UV-induced decarbonylation, and FTIR spectra of 1-phenyl-1,2 propanedione in solid xenon and in the low temperature amorphous phase
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Conformational flexibility, UV-induced decarbonylation, and FTIR spectra of 1-phenyl-1,2 propanedione in solid xenon and in the low temperature amorphous phase

机译：固态氙和低温非晶相中1-苯基-1，2-丙二酮的构象柔韧性，UV诱导的脱羰作用和FTIR光谱

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1-Phenyl-1,2-propanedione has been isolated in low-temperature xenon matrixes and studied by FTIR spectroscopy, supported by DFT(B3LYP)/6-311++G(d,p) calculations. In good agreement with previous electron diffraction data [Shen, Q.; Hagen, K. J. Phys. Chem. 1993, 97, 985], the calculations predicted the existence of only one stable conformation for the compound, in which the O=C-C=O dihedral angle is 135.6 degrees. On the other hand, the experimental data clearly reveals that, in the as-deposited xenon matrixes (T = 20 K), there is a distribution of molecules with different O=C-C=O dihedral angles around the equilibrium value. This distribution results from the efficient trapping of the conformational distribution existing in the gas phase, prior to deposition, which is determined by the low frequency, large amplitude torsional vibration around the C-C central bond. Upon annealing to higher temperatures (T similar to 45 K), the initially trapped conformational distribution can be modified in a certain degree, favoring more polar structures (corresponding to smaller O=C-C=O dihedral angles), as a result of the interactions with the matrix media. Irradiation of the matrix with UV light (lambda > 235 nm) led to decarbonylation of the compound, with generation of acetophenone and carbon monoxide, with an almost complete consumption of the reagent after 1100 min of irradiation (k = 2.8 x 10(-2) min.(-1)). Aggregation of the compound resulting from the matrix warming was also investigated, providing useful information for interpretation of the spectroscopic data obtained for the low-temperature amorphous state of the neat compound.
机译：1-苯基-1,2-丙二酮已在低温氙气基质中分离出来，并通过FTIR光谱研究，得到DFT（B3LYP）/ 6-311 ++ G（d，p）计算的支持。与先前的电子衍射数据[Shen，Q .; Hagen，K.J.Phys。化学1993，97，985]，计算预测该化合物仅存在一种稳定构象，其中O = C-C = O二面角为135.6度。另一方面，实验数据清楚地表明，在沉积的氙气矩阵（T = 20 K）中，在平衡值附近存在具有不同O = C-C = O二面角的分子分布。这种分布是由于在沉积之前有效捕获气相中存在的构象分布而产生的，这是由围绕C-C中心键的低频大振幅扭转振动决定的。在退火至较高温度（T类似于45 K）时，由于与C相互作用，可以在一定程度上修饰最初捕获的构象分布，从而有利于极性更大的结构（对应于较小的O = CC = O二面角）。矩阵媒体。用紫外线（λ> 235 nm）照射基质会导致化合物脱羰基化，并生成苯乙酮和一氧化碳，并且在1100分钟的照射后几乎完全消耗了试剂（k = 2.8 x 10（-2） ）分钟（-1））。还研究了由基质升温引起的化合物的聚集，为解释纯化合物的低温非晶态所获得的光谱数据提供了有用的信息。

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