Jankowiak Aleksandra, Kaszynski Piotr
Organic Materials Research Group, Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA.
J Org Chem. 2009 Oct 2;74(19):7441-8. doi: 10.1021/jo901522r.
A series of eight 4-substituted 1-(adamantane-1-carbonyloxy)pyridine-2(1H)-thiones (1, X = H, OC(7)H(15), Me, CF(3), SC(3)H(7), CN, COOMe, and Cl) was prepared and characterized by UV-vis spectroscopy in MeCN and cyclohexane. The observed lowest energy transition, designated as pi(CS) --> pi*(ring), exhibits a substantial substituent effect and lambda(max) ranges from 333 (X = OC(7)H(15)) to 415 nm (X = CN). Experimental lambda(max) values for all esters except for 1b (X = OC(7)H(15)) correlate with the sigma(p)(-) parameter (rho = 0.41 +/- 0.03, r(2) = 0.95). In contrast, the energy of the absorption band at about 295 nm, designated as pi(CS) --> pi*(CS), is practically substituent independent. Both absorption bands exhibit a modest negative solvatochromic effect. The experimental absorption energies correlate better with excitation energies calculated for N-acetyloxy analogues 2 with the ZINDO//DFT than with the TD-DFT//DFT method. Calculations for a series of 12 N-acetates 2 predict the most blue-shifted pi --> pi* transition for the alkoxy substituent and most red-shifted for the NO(2) group relative to the parent 2a (X = H).
制备了一系列八个4-取代的1-(金刚烷-1-羰氧基)吡啶-2(1H)-硫酮(1, X = H、OC(7)H(15)、Me、CF(3)、SC(3)H(7)、CN、COOMe和Cl)，并通过在乙腈和环己烷中的紫外-可见光谱对其进行了表征。观察到的最低能量跃迁，指定为π(CS)→π*(环)，表现出显著的取代基效应，λ(max)范围为333( X = OC(7)H(15))至415 nm( X = CN)。除1b( X = OC(7)H(15))外，所有酯的实验λ(max)值与σ(p)(-)参数相关(ρ = 0.41±0.03，r(2)= 0.95)。相反，在约295 nm处的吸收带能量，指定为π(CS)→π*(CS)，实际上与取代基无关。两个吸收带都表现出适度的负溶剂化显色效应。与TD-DFT//DFT方法相比，实验吸收能量与用ZINDO//DFT计算的N-乙酰氧基类似物2的激发能量相关性更好。对一系列12种N-乙酸酯2的计算预测，相对于母体2a( X = H)，烷氧基取代基的π→π跃迁最蓝移，而NO(2)基团的π→π跃迁最红移。
