Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany.
J Phys Chem A. 2010 Dec 9;114(48):12600-4. doi: 10.1021/jp109949y. Epub 2010 Nov 11.
Electronic spectra of the S(1)←S(0) transition of dimers of protonated benzaldehyde (BZH(+)) with Ar and N(2) are recorded by resonance-enhanced photodissociation in a tandem mass spectrometer. The S(1) origins observed are shifted to higher frequency upon complexation with Ar (ΔS(1) = 300 cm(-1)) and N(2) (ΔS(1) = 628 cm(-1)). Ab initio calculations at the CC2/aug-cc-pVDZ level suggest an assignment to H-bonded dimers of L = Ar and N(2) binding to the cis isomer of O-protonated BZH(+), yielding values of ΔS(1) = 242 and 588 cm(-1) for cis-BZH(+)-L(H). Electronic ππ* excitation results in a substantial increase of the proton affinity of BZH(+), which in turn destabilizes the intermolecular H-bonds to the inert ligands by 35%. The drastic effects of electronic ππ* excitation on the geometric and electronic structure as well as the strength and anisotropy of the intermolecular potential (H-bonding and π-bonding) are investigated.
电子光谱的 S(1)←S(0) 跃迁的质子化苯甲醛 (BZH(+)) 与 Ar 和 N(2) 的二聚体是记录下来的共振增强光解在串联质谱仪。S(1) 起源观察到的是复杂的 Ar (ΔS(1) = 300 cm(-1)) 和 N(2) (ΔS(1) = 628 cm(-1)) 向更高的频率移动。从头算计算在 CC2/aug-cc-pVDZ 水平建议分配给氢键的 L = Ar 和 N(2) 结合的 cis 异构体 O-质子化 BZH(+),产生的值 ΔS(1) = 242 和 588 cm(-1) cis-BZH(+)-L(H)。电子 ππ* 激发导致苯甲醛质子亲和能的显著增加，这反过来又通过 35%破坏了对惰性配体的分子间氢键。电子 ππ* 激发对几何和电子结构以及分子间势能 (氢键和 π 键) 的强度和各向异性的剧烈影响进行了研究。
