From Metal‐Metal Bonding to Supra‐Metal‐Metal Bonding Directed Self‐Assembly: Supramolecular Architectures of Group 10 and 11 Metals with Ligands from Mono‐ to Poly‐Pyrazoles

Abstract

The supramolecular architectures of pyrazole ligands with polynuclear metal centers have established a wide variety of constructing motifs. This review focuses on the metal‐metal bonding and Supra‐Metal‐Metal Bonding directed self‐assembly of supramolecular architectures of pyrazole ligands ranging from simple mono‐pyrazoles and derivatives to bipyrazoles and polypyrazoles with group 10 and 11 elements. The utility of the constructing motifs (μ‐pyrazolato‐N,N′)2 doubly‐bridged dimetal corners in the metal‐metal‐bonding directed self‐assembly approaches with spontaneous deprotonation from bipyrazole to tripyrazole and tetrapyrazolyl calix[4]arene ligands, metallomacrocyclic and cage‐like complexes have been synthesized. The proton switching programmable self‐assembly strategy using pyrazole‐based bifunctional ligands has been developed by Yu. They have obtained organic homo‐ or hetero‐metallic supramolecular complexes from macrocycles, cages, to one dimensional polymers.

Designing a highly stable coordination-driven metallacycle for imaging-guided photodynamic cancer theranostics

“…The spontaneous deprotonation of the 3,5-dimethylpyrazole group occurred upon coordination to the dipalladium center during the self-assembly process in solution, which is consistent with previous reports. 52,53,56 The average Pd/Pd separation in the dimetallic clips was 3.16Å, indicative of the existence of a weak Pd II -Pd II interaction (in the range of 2.60-3.30Å). The dihedral angles of two pyrazolate planes in the dipalladium corners are 88.1 and 89.0 respectively.…”

“…1A). Due to the formation of dipalladium clips during a spontaneous deprotonation assembly process, 52,53 metallacycle 2 exhibits unusual chemical stability toward acidic conditions. Photophysical properties, singlet oxygen production and the bio-imaging and intracellular translocation of metallacycle 2 in vitro and vivo have been thoroughly studied.…”

Chromium(III)-pyrazole complexes. X-Ray crystal structures, 1H NMR investigation of ligand fluxional behavior and EPR studies

“…For this potential to be realized, the finer details of their magnetic structures need to be elucidated, so that their magnetic relaxation pathways can be better understood and their relaxation characteristics improved. We have long studied the coordination chemistry of pyrazoles (pzH and pz*H = substituted pyrazole), a versatile group of N-donor ligands, adopting various coordination modes and readily tunable with regard to their steric bulk and electron donor/acceptor properties via judicious substitution at their 3-, 4-, 5-positions [5][6][7]. Furthermore, mononuclear transition metal-pyrazole complexes are convenient starting materials for the synthesis of larger polynuclear homometallic and heterometallic pyrazolato species, achieved by deprotonation of the κ 1 -pz*H to µ-κ 2 -pz* -(Scheme 1).…”

Self‐Assembly and C−H⋅⋅⋅Anion Hydrogen Bonding of Palladium(II)‐based Metallacalixarenes Using Pyridyl‐ or Phenyl‐Bridged Di‐Naphthoimidazoles

“…Over the past two decades, metal-directed self-assembly has led to the explosive development of numerousm etal-organic or organometallic macrocyclic and cage like complexes with high symmetrical structures. [1][2][3][4][5] These metallosupramolecular systemsh ave displayed attractive properties in molecular recognition, catalysis, redoxactivity,m agnetism, luminescence, and electron transfer,e tc. [6] In contrast, the metallo-architectures with low-symmetries such as bowl-shaped molecules are still challenging, which have attracted particular attention be-cause they are capable of behaving as structurala nalogues of the organic hosts calixarenes.…”

“…[6] In contrast, the metallo-architectures with low-symmetries such as bowl-shaped molecules are still challenging, which have attracted particular attention be-cause they are capable of behaving as structurala nalogues of the organic hosts calixarenes. [7] Lippert reported the first metal analogue of calix [4]arene self-assembled by cis-protected Pt II complexes and pyrimidine ligand in 1992. [8] According to Lippert, [9] ametallacalixarene can be considered as aspecial heterocalixarene, namely am etal analogue of calixarenes, in which the methylene-bridging entity of the classical calixarene is replacedb yametal center.I nabroad sense, the metal-assembled architectures with calixarene features (such as the tunable cavities and mobile conformations) could be categorized as metallacalixarenes or inorganic calixarenes.…”