One-pot Azide-alkyne Cycloaddition Research Articles

Synthesis, characterization, and comparison of two new copper(II) complexes containing Schiff-base and diazo ligands as new catalysts in CuAAC reaction

Two copper(II) complexes were synthesized through the reaction of Cu(OAc)2·H2O with a Schiff-base ligand (1-(((3,4-dichlorophenyl)imino)methyl)naphthalen-2-ol) and a diazo ligand (1-((3,4-dichlorophenyl)diazenyl)naphthalen-2-ol) in methanol. The complexes and ligands were characterized employing elemental analysis and electronic spectra. In addition, the ligands were fully characterized by using several 1D and 2D NMR techniques. Single crystal X-ray crystallography was also used for the characterization of some of these materials. Due to finding out the effect of Schiff-base and diazo ligands nature on the catalytic activity, the complexes were catalytically compared in one-pot azide-alkyne cycloaddition reaction in water. Furthermore, computational studies were performed on ligands and complexes for further understanding of the relationship between structure, bonding, and reactivity of these new materials.

SBA-15-supported Cu (II)/Schiff-base complex as an efficient and recyclable catalyst for one-pot azide-alkyne cycloaddition reaction

A new complex of copper (II) was synthesized through the reaction of a Schiff-base, 4-(((2-hydroxyethyl)imino)methyl)phenol, with CuCl2·2H2O and, then, immobilization on SBA-15 support. Both immobilized and free copper complexes were characterized using different techniques such as FT-IR, elemental analysis (CHN), SEM, XRD and TEM, and were utilized as catalysts in one-pot azide-alkyne cycloaddition (AAC) reaction. Both catalysts showed high activity in conversion of various substrates to corresponding triazole compounds. The reaction was performed in water under mild condition and without any extra additives. The prepared catalyst was recovered and reused in 5 runs without any significant loss of activity.

Two new copper(II) complexes with chelating N,O-type bidentate ligands: Synthesis, characterization, crystal structure and catalytic activity in azide–alkyne cycloaddition reaction

Tetra-coordinated copper(II) complexes, [CuL2] and [Cu(phox)2], were synthesized by reaction of 1-((4-bromophenylimino)methyl)naphthalen-2-ol, HL, and 2-(2′-hydroxyphenyl)-2-oxazoline, Hphox, ligands with copper acetate, respectively. The complexes were characterized using FT-IR spectroscopy, elemental analyses, and their solid state structures were confirmed by single crystal X-ray diffraction. The catalytic activity of the complexes was evaluated in one-pot azide–alkyne cycloaddition (AAC) click reaction in water without need of any additional agent. The [CuL2] complex showed high catalytic activity in this reaction‌‌‌ and 1,2,3-triazole derivatives were produced in moderate to good yields.

Hybrid NS ligands supported Cu(i)/(ii) complexes for azide–alkyne cycloaddition reactions

Three copper complexes of nitrogen-sulfur donor ligands, [CuBr₂(L1)] (1), [CuCl₂(L2)₂] (2) and [Cu₂I₂(L3)]n (3) (L1 = bis(2-cyclohexylsulfanylethyl)amine, L2 = 2-(benzylsulfanylmethyl)pyridine and L3 = 2-(4-pyridylsulfanylmethyl)pyridine), have been synthesized and characterized by single-crystal X-ray diffraction (XRD), powder XRD and TGA analysis. Complexes 1 and 2 are mononuclear Cu(II) complexes and are EPR active with distorted square-pyramidal and octahedral geometry, respectively. Complex 3 is a two-dimensional tetrahedral Cu(I) coordination polymer with 16- and 20-membered metallocycles. These complexes show good catalytic activities for one-pot azide-alkyne cycloaddition reactions in CH₃OH-H₂O.

Effects of Trehalose Polycation End-Group Functionalization on Plasmid DNA Uptake and Transfection

In this study, we have synthesized six analogs of a trehalose-pentaethylenehexamine glycopolymer (Tr4) that contain (1A) adamantane, (1B) carboxy, (1C) alkynyl-oligoethyleneamine, (1D) azido trehalose, (1E) octyl, or (1F) oligoethyleneamine end groups and evaluated the effects of polymer end group chemistry on the ability of these systems to bind, compact, and deliver pDNA to cultured HeLa cells. The polymers were synthesized in one-pot azide-alkyne cycloaddition reactions with an adaptation of the Carothers equation for step-growth polymerization to produce a series of polymers with similar degrees of polymerization. An excess of end-capping monomer was added at the end of the polymerizations to maximize functionalization efficiency, which was evaluated with GPC, NMR, and MALDI-TOF. The polymers were all found to bind and compact pDNA at similarly low N/P ratios and form polyplexes with plasmid DNA. The effects of the different end group structures were most evident in the polyplex internalization and transfection assays in the presence of serum as determined by flow cytometry and luciferase gene expression, respectively. The Tr4 polymers end-capped with carboxyl groups (1B) (N/P = 7), octyne (1E) (N/P = 7), and oligoethyleneamine (1F) (N/P = 7), were taken into cells as polyplex and exhibited the highest levels of fluorescence, resulting from labeled plasmid. Similarly, the polymers end-functionalized with carboxyl groups (1E at N/P = 7), octyl groups (1E at N/P = 15), and in particular oligoethyleneamine groups (1F at N/P = 15) yielded dramatically higher reporter gene expression in the presence of serum. This study yields insight into how very subtle structural changes in polymer chemistry, such as end groups can yield very significant differences in the biological delivery efficiency and transgene expression of polymers used for pDNA delivery.