Multifunctional Deuterated and Tritiated ‘Click’ Molecular Probes via Palladium-Mediated Reductive Deiodination of 5-Iodo-1,2,3-Triazoles
摘要:
Tritiated compounds are invaluable tools for in vitro and in vivo studies on bioactive molecules. Here we describe a click-chemistry'-based strategy for deuteration and tritiation of multifunctional compounds and multimodal molecular imaging probes. The method relies on a palladium-mediated reductive deiodination of 5-iodo-1,2,3-triazoles in the presence of NaBD4, deuterium or tritium gas.
Strong, Size-Selective, and Electronically Tunable C−H···Halide Binding with Steric Control over Aggregation from Synthetically Modular, Shape-Persistent [3<sub><i>4</i></sub>]Triazolophanes
作者:Yongjun Li、Amar H. Flood
DOI:10.1021/ja803341y
日期:2008.9.10
A series of shape-persistent [3(4)]triazolophanes bearing t-butyl or triethylene glycol (OTg) substituents on the phenylene linkers have been prepared in a modular manner from simple building blocks. Triazolophane-halide binding affinities were determined using UV titrations in order to help in understanding the driving forces behind the large receptor-anion binding strengths supported solely by CH hydrogen-bond donors. The fixed size of the central cavity provides a means for selective recognition of Cl- and Br- anions with large binding strengths (K-a > 1 000 000 M-1; Delta G > -8.5 kcal mol(-1)). The smaller F- and larger I- anions are bound less tightly by similar to 1 and similar to 3 orders of magnitude, respectively. The four triazole-based H-bond donors are believed to be of primary importance, while the four phenylene CH H-bond donors take on a secondary role. Consistent with this idea, the binding affinity can be tuned by as much as 1 kcal mol-1 by changing the character of the four phenylene-based substituents from more (OTg) to less (t-butyl) electron-donating. Preorganization was also found to play a central role, on the basis of comparisons with a foldamer analogue that shows much-reduced binding. Aggregation was facilitated as the substituents were changed from t-butyl to OTg, increasing the degree of self-association from K-E approximate to 0 to 230 M-1 in CD2Cl2. Diffusion NMR experiments established aggregation as opposed to dimerization. These findings indicate the importance of the cavity size for selective anion recognition as well as the role of the phenylene linkers in tuning the binding strengths and modulating the aggregation of the [3(4)]triazolophanes.
Pure CH Hydrogen Bonding to Chloride Ions: A Preorganized and Rigid Macrocyclic Receptor
作者:Yongjun Li、Amar H. Flood
DOI:10.1002/anie.200704717
日期:2008.3.25
‘Cleft-form’ electrochemical anion chemosensor with amide and triazole donor groups
作者:Qian-Yong Cao、Tuhin Pradhan、Min Hee Lee、Dong Hoon Choi、Jong Seung Kim
DOI:10.1016/j.tetlet.2012.06.118
日期:2012.9
A novel 'cleft-form' electrochemical anion receptor bearing amide and triazole donor groups, 1, has been synthesized and characterized. Among various anions, 1 shows a significant anodic shift response for H2PO4- and F-, with its multiple N-H center dot center dot center dot anion and C-H center dot center dot center dot anion interactions, which is supported by theoretical calculation and NMR titration results. (C) 2012 Elsevier Ltd. All rights reserved.
A Pyrrolyl-Based Triazolophane: A Macrocyclic Receptor With CH and NH Donor Groups That Exhibits a Preference for Pyrophosphate Anions
作者:Jonathan L. Sessler、Jiajia Cai、Han-Yuan Gong、Xiaoping Yang、Jonathan F. Arambula、Benjamin P. Hay
DOI:10.1021/ja107098r
日期:2010.10.13
A pyrrolyl-based triazolophane, incorporating CH and NH donor groups, acts as a receptor for the pyrophosphate anion in chloroform solution. It shows selectivity for this trianion, followed by HSO4- > H2PO4- > Cl- > Br- (all as the corresponding tetrabutylammonium salts), with NH-anion interactions being more important than CH-anion interactions. In the solid state, the receptor binds the pyrophosphate anion in a clip-like slot via NH and CH hydrogen bonds.