We employ low-temperature matrix-isolation FTIR spectroscopy and quantum chemical calculations to study the interaction between nucleobase uracil and coronene which models the graphene surface. To observe the dimer FTIR spectrum, we use a quartz microbalance that allows us to produce matrix samples with precisely determined concentrations of coronene and uracil (with the concentration ratio of 2.5:1:1000 for coronene:uracil:argon). The interaction between coronene and uracil results in spectral shifts of uracil spectral bands. These shifts do not exceed 10 cm⁻¹. The maximum shifts are observed for the C=O stretching and NH out-of-plane vibrations of uracil. The structures and interaction energies of stacked and H-bonded coronene-uracil complexes are calculated at the DFT/B3LYP(GD3BJ)/aug-cc-pVDZ and MP2/aug-cc-pVDZ levels of theory. In total, 19 stable stacked and two H-bonded coronene-uracil dimer structures are found in the calculations. The interaction energy obtained for the most stable stacked dimer is −12.1 and −14.3 kcal/mol at the DFT and MP2 levels, respectively. The interaction energies of the H-bonded dimers do not exceed − 3 kcal/mol. The IR spectra of the studied monomeric molecules and of all the dimers are calculated at the DFT/B3LYP(GD3BJ)/aug-cc-pVDZ level of theory. The spectral shifts of the most stable stacked coronene-uracil dimer obtained in the calculations are in good agreement with the experimental results.

中文翻译：

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嵌入氩气基质中的苯并尿嘧啶配合物：FTIR光谱和量子力学计算

我们采用低温基质分离FTIR光谱和量子化学计算来研究核碱基尿嘧啶和可伦烯之间的相互作用，后者可模拟石墨烯表面。为了观察二聚体FTIR光谱，我们使用石英微量天平，该石英微量天平使我们能够生产基质样品，其中样品中的冠冕烯和尿嘧啶浓度精确确定（冠冕烯：尿嘧啶：氩气的浓度比为2.5：1：1000）。冠冕烯和尿嘧啶之间的相互作用导致尿嘧啶光谱带的光谱移动。这些偏移不超过10 cm ^-1。对于尿嘧啶的C ＝ O拉伸和NH面外振动观察到最大位移。在理论的DFT / B3LYP（GD3BJ）/ aug-cc-pVDZ和MP2 / aug-cc-pVDZ的水平上计算了堆叠的和H键合的异戊二烯-尿嘧啶配合物的结构和相互作用能。在计算中总共发现了19个稳定的堆叠结构和2个H键合的异戊二烯-尿嘧啶二聚体结构。在DFT和MP2浓度下，最稳定的堆叠二聚体获得的相互作用能分别为-12.1 kcal / mol和-14.3 kcal / mol。H键合的二聚体的相互作用能不超过− 3 kcal / mol。研究的单体分子和所有二聚体的红外光谱是在理论的DFT / B3LYP（GD3BJ）/ aug-cc-pVDZ水平下计算的。