Evans–Showell-type polyoxometalate-based metal–organic complexes with novel 3D structures constructed from flexible bis-pyrazine–bis-amide ligands and copper metals: syntheses, structures, and fluorescence and catalytic properties

Abstract

Two 3D Evans–Showell-type POM-based copper–bis-pyrazine–bis-amide complexes show good heterogeneous catalytic activity for the oxidation of benzyl alcohol.

CuII Complexes and Coordination Polymers with Pyridine or Pyrazine Amides and Amino Benzamides—Structures and EPR Patterns

“…In metalloenzymes, carboxylate side chains of the peptide are very frequent ligands and were preferably coordinated by hard metal ions, as expected. In contrast to this, carboxamide side chains were less preferred as ligands in metalloenzymes [34][35][36], in agreement with the observation that the carboxamide function coordinates only effectively in chelate ligands as 2-pyridine or 2-pyrazine carboxamides [1][2][3]5,6,[15][16][17][18][19][20][22][23][24][25][26]32,[37][38][39][40][41].…”

“…Non-chelated Oamide binding to Cu II was found in the axial (weak) positions only in one compound (2) and no NH2amide coordination, in line with the observation that amide functions in amino acids do not represent an important class of ligands in metalloproteins [34][35][36] and the poor non-biologic coordination chemistry of amides and Cu [33,35,37]. Indeed, searching the CCDC database, gave only the Cu II complex [Cu(L)2(OH)2] containing two chelating pyrazine-2,3dicarboxamide ligands with Cu-NH2amide bonds [49].…”

“…Pyridine carboxamides, pyrazine carboxamides and amino-benzamides (Scheme 1) are interesting ditopic ligands for Cu II coordination chemistry . One reason is their use as versatile building blocks in coordination polymers and MOFs for various applications [1][2][3]8,9,[11][12][13]16,20,21,26,27]. Another important reason is the biological relevance of some of the ligands used in this study (Scheme 1) [4][5][6]17,18,24,33].…”

Metal–Organic Framework Based on Heptanuclear Cu–O Clusters and Its Application as a Recyclable Photocatalyst for Stepwise Selective Catalysis

“…The oxidation of alcohols to the corresponding carbonyl compounds is a critical transformation in organic synthesis. − Many catalytic systems, homogeneous or heterogeneous, have been developed for the oxidation of alcohols, forming corresponding aldehydes, carboxylic acids, or esters depending on the level of oxidation and esterification, with poor or satisfactory yields depending on the catalytic system. ,,− Despite the progresses made toward this end, available catalysts are still limited with versatile disadvantages, such as the need of harsh reaction conditions, the involvement of noble or toxic metals, the use of costly cocatalysts, and poor recyclability. − To the best of our knowledge, there are no attempts utilizing visible light to mediate the oxidation reaction. The development of a photocatalytic system utilizing a highly efficient heterogeneous catalyst with good recyclability is of great importance in terms of green chemistry. − …”

Cobalt complexes tuned by Anderson-type polyoxometalates and bis-amide derivative ligands featuring a ‘V’-like connector for efficient ampere sensing and the visible-light catalytic reduction of Cr(vi)

“…For instance, two Evans-type POMbased complexes constructed from two different bis-pyridinebis-amide ligands, synthesized by Li et al showed excellent catalytic oxidation performance. 29 By introducing the bis-pyrimidine-bis-amide ligand N,N′-bis-(4-pyrimidinecarboxamido)-1,2-ethane (4-H 2 dpye), two Keggin-type POM-based MOCs were successfully synthesized by our group with excellent electrochemical sensing behavior, which could be used as supercapacitor materials. 30 In view of this, two new bis-pyridine-bis-amide ligands, namely 4,4′-bis(3-pyridinecarboxamide)phenylmethane (L 1 ) and, 4,4′-bis(3-pyridinecarboxamide)phenylketone (L 2 ), were designed and synthesized (Scheme 1), and further used to assemble with Anderson-type POMs and Co II ions.…”