Nucleosides and Nucleotides. 182. Synthesis of Branched Oligodeoxynucleotides with Pentaerythritol at the Branch Point and Their Thermal Stabilization of Triplex Formation<sup>1</sup>
To find an oligodeoxynucleotide (ODN) with tripler stabilization capability, we designed and synthesized novel branched ODNs I and 2 with pentaerythritols at their branch points. Branched ODNs 1 and 2 were synthesized on a solid support using bis(phosphoramidite) 11. The stability of the triplexes, formed by branched ODNs 1 and 2 with (dA)(21) or (dT)(21) was studied by thermal denaturation. Branched ODN 1 formed a stable parallel T.AT-type tripler with (dA)(21) (T-m = 38.9 degrees C) in a buffer of 0.01 M sodium phosphate (pH 7.0) containing 0.5 M NaCl and 0.02 M MgCl2, while branched ODN 2 formed a stable antiparallel A.AT-type tripler with (dT)(21) (T-m = 44.2 degrees C) in the same buffer. The formation of these triplexes was also confirmed by circular dichroism (CD) measurements and a gel retardation assay.
Construction of Segregated Arrays of Multiple Donor and Acceptor Units Using a Dendritic Scaffold: Remarkable Dendrimer Effects on Photoinduced Charge Separation
visualization of a petal-like structure of DP12 superset Py2F3. Photoexcitation of the zinc porphyrin units in DPm superset Py2Fn results in a zinc porphyrin-to-fullerene electron transfer to generate a chargeseparation. The charge-separation rate constant (kCS) in CH2Cl2 at 20 degrees C increases from 0.26 x 10(10) to 2.3 x 10(10) s(-1) upon increment of m and n, whereas the charge-recombination rate constant
附加有多个锌卟啉单元(DPm,m [锌卟啉单元数] = 6、12 和 24)的树枝状分子捕获带有多个富勒烯单元(Py2Fn,n [C60 单元数] = 1-3)的联吡啶化合物,提供配位复合物 DPm 超集 Py2Fn,在其表面上具有由空间隔离的供体和受体阵列组成的光敏层。复合物 DPm 超集 Py2Fn 足够稳定(K [平均结合亲和力] = 1.1 x 10(6)-4.4 x 10(6) M(-1) 在 CHCl3 中,在 25 摄氏度),可通过凝胶渗透色谱分离。UHV-STM 显微镜可以清晰地显示 DP12 超集 Py2F3 的花瓣状结构。DPm 超集 Py2Fn 中锌卟啉单元的光激发导致锌卟啉到富勒烯的电子转移以产生电荷分离。随着 m 和 n 的增加,20 摄氏度 CH2Cl2 中的电荷分离速率常数 (kCS) 从 0.26 x 10(10) 增加到 2.3 x 10(10) s(-1),而电荷复合速率常数