Crystal Structures,Magnetic Properties and Catecholase‐Like Activities of μ‐Alkoxo‐μ‐Carboxylato Double Bridged Dinuclear and Tetranuclear Copper(II) Complexes

One μ‐alkoxo‐μ‐carboxylato bridged dinuclear copper(II) complex, [Cu₂(L¹)(μ‐C₆H₅CO₂)] ( 1 )(H₃L¹ = 1,3‐bis(salicylideneamino)‐2‐propanol)), and two μ‐alkoxo‐μ‐dicarboxylato doubly‐bridged tetranuclear copper(II) complexes, [Cu₄(L¹)₂(μ‐C₈H₁₀O₄)(DMF)₂]·H₂O ( 2 ) and [Cu₄(L²)₂(μ‐C₅H₆O₄]·2H₂O·2CH₃CN ( 3 ) (H₃L² = 1,3‐bis(5‐bromo‐salicylideneamino)‐2‐propanol)) have been prepared and characterized. The single crystal X‐ray analysis shows that the structure of complex 1 is dimeric with two adjacent copper(II) atoms bridged by μ‐alkoxo‐μ‐carboxylato ligands where the Cu···Cu distances and Cu‐O(alkoxo)‐Cu angles are 3.5 11 Å and 132.8°, respectively. Complexes 2 and 3 consist of a μ‐alkoxo‐μ‐dicarboxylato doubly‐bridged tetranuclear Cu(II) complex with mean Cu‐Cu distances and Cu‐O‐Cu angles of 3.092 Å and 104.2° for 2 and 3.486 Å and 129.9° for 3 , respectively. Magnetic measurements reveal that 1 is strong antiferromagnetically coupled with 2J =‐210 cm^?1 while 2 and 3 exhibit ferromagnetic coupling with 2J = 126 cm^?1 and 82 cm^?1 (averaged), respectively. The 2J values of 1–3 are correlated to dihedral angles and the Cu‐O‐Cu angles. Dependence of the pH at 25 °C on the reaction rate of oxidation of 3,5‐di‐tert‐butylcatechol (3,5‐DTBC) to the corresponding quinone (3,5‐DTBQ) catalyzed by 1–3 was studied. Complexes 1–3 exhibit catecholase‐like active at above pH 8 and 25 °C for oxidation of 3,5‐di‐tert‐butylcatechol.     

Structural investigation of one‐ and two‐dimensional coordination polymers based on cobalt–bis(dioxolene) units and 1‐hydroxy‐1,2,4,5‐tetrakis(pyridin‐4‐yl)cyclohexane

The combination of cobalt, 3,5‐di‐tert‐butyldioxolene (3,5‐dbdiox) and 1‐hydroxy‐1,2,4,5‐tetrakis(pyridin‐4‐yl)cyclohexane (tpch) yields two coordination polymers with different connectivities, i.e. a one‐dimensional zigzag chain and a two‐dimensional sheet. Poly[[bis(3,5‐di‐tert‐butylbenzene‐1,2‐diolato)bis(1,5‐di‐tert‐butyl‐4‐oxocyclohexa‐2,5‐dien‐1‐yl‐3‐olato)[μ₄‐1‐hydroxy‐1,2,4,5‐tetrakis(pyridin‐4‐yl)cyclohexane]cobalt(III)]–ethanol–water 1/7/5], {[Co₂(C₁₄H₂₀O₂)₄(C₂₆H₂₄N₄O)]·7C₂H₅OH·5H₂O}_n or {[Co₂(3,5‐dbdiox)₄(tpch)}·7EtOH·5H₂O}_n, is the second structurally characterized example of a two‐dimensional coordination polymer based on linked {Co(3,5‐dbdiox)₂} units. Variable‐temperature single‐crystal X‐ray diffraction studies suggest that catena‐poly[[[(3,5‐di‐tert‐butylbenzene‐1,2‐diolato)(1,5‐di‐tert‐butyl‐4‐oxocyclohexa‐2,5‐dien‐1‐yl‐3‐olato)cobalt(III)]‐μ‐1‐hydroxy‐1,2,4,5‐tetrakis(pyridin‐4‐yl)cyclohexane]–ethanol–water (1/1/5)], {[Co(C₁₄H₂₀O₂)₂(C₂₆H₂₄N₄O)]·C₂H₅OH·5H₂O}_n or {[Co(3,5‐dbdiox)₂(tpch)]·EtOH·5H₂O}_n, undergoes a temperature‐induced valence tautomeric interconversion.     

两种新型μ－氧桥联－双铁(III)席夫碱配合物：X-衍射分析，IR, UV-Vis, CD光谱，磁性质和电化学性质

热力学稳定的带有大环配体的μ－氧桥联－双铁配合物，由于其两个铁中心之间的有趣的电子结构和磁相互作用而受到广泛关注。μ－氧桥联－双铁席夫碱配合物，[{Fe(tbusalphn)}₂(μ-o)] (1)和[{Fe(R,R-salchxn)}₂(μ-o)] (2), 通过用咪唑或N－甲基咪唑的水溶液处理相应的单核铁氯化物，Fe(L)Cl，而获得。1和2的晶体结构通过x-射线结构分析而被确定。1属于三斜晶系，P－1空间群。2属于单斜晶系，P2₁/c空间群。由于1的配体带有庞大的叔丁基取代基，导致形成μ－氧桥联－双铁配合物时的空间拥挤，因此，其Fe-O-Fe夹角为176.5 ^o，几乎成平角。而2则由于配体上没有庞大的取代基，其Fe-O-Fe夹角为149.6^o，明显小于1的Fe-O-Fe夹角。 本文还对两种μ－氧桥联－双铁席夫碱配合物及相应的单核铁氯化物的红外光谱、紫外－可见吸收光谱及圆二色光谱性质进行了研究。与相应的单体铁配合物相比较，生成μ－氧桥联－双铁席夫碱配合物后，出现一新的红外吸收带，归属于ν_Fe-O-Fe振动。有趣的是，其数值与Fe-O-Fe夹角大小相对应。1和2除具有明显不同的Fe-O-Fe夹角外，它们的圆二色光谱却是相似的。 对1和2的磁性质研究表明，在这类化合物中两个铁(III)离子之间存在着强烈的分子内抗铁磁性偶合作用。另外，本文还采用循环伏安法对1和2的电化学性质进行了研究。     

A Sterically Hindered Phosphonic Acid with a Hydrogen‐Bonded Cage Structure: [4‐tert‐Bu‐2,6‐Mes2‐C6H2P(O)(OH)2·H2O]4

The synthesis and molecular structure of the novel phosphonic acid 4‐tert‐Bu‐2,6‐Mes₂‐C₆H₂P(O)(OH)₂ ( 1 ) is reported. Compound 1 crystallizes in form of its monohydrate as a hydrogen‐bonded cluster ( 1·H₂O )₄ comprizing four phosphonic acid molecules (O···O 2.383(3)‐3.006(4) Å). Additionally, sterically hindered terphenyl‐substituted phosphorus compounds of the type 4‐tert‐Bu‐2,6‐Mes₂‐C₆H₂PR(O)(OH) ( 5 , R = H; 7 , R = O₂CC₆H₄‐3‐Cl; 9 , R = OEt) were prepared, which all show dimeric hydrogen‐bonded structures with O···O distances in the range 2.489(2)–2.519(3) Å. Attempts at oxidizing 5 using H₂O₂, KMnO₄, O₃, or Me₃NO in order to give 1 failed. Crystallization of 5 in the presence of Me₃NO gave the novel hydrogen bonded aggregate 4‐tert‐Bu‐2,6‐Mes₂‐C₆H₂PH(O)(OH)·ONMe₃ ( 6 ) showing an O–H···O distance of 2.560(4) Å.     

Tuning the Stability and Reactivity of Metal‐bound Alkylperoxide by Remote Site Substitution of the Ligand

An alkylperoxonickel(II) complex with hydrotris(3,5‐diisopropyl‐4‐bromo‐1‐pyrazolyl)borate, [Ni^II(OOtBu)(Tp^iPr2,Br)] ( 3a ), is synthesized, and its chemical properties are compared with those of the prototype non‐brominated ligand derivative [Ni^II(OOtBu)(Tp^iPr2)] ( 3b ; Tp^iPr2=hydrotris(3,5‐diisopropyl‐1‐pyrazolyl)borate). Same synthetic procedures for the prototype 3b and its precursors can be employed to the synthesis of the Tp^iPr2,Br analogues. The dimeric nickel(II)‐hydroxo complex, [(Ni^IITp^iPr2,Br)₂(μ‐OH)₂] ( 2a ), can be synthesized by the base hydrolysis of the labile complexes [Ni^II(Y)(Tp^iPr2,Br)] (Y=NO₃ ( 1a ), OAc ( 1a′ )), which are obtained by the metathesis of NaTp^iPr2,Br with the corresponding nickel(II) salts, and the following dehydrative condensation of 2a with the stoichiometric amount of tert‐butylhydroperoxide yields 3a . The unique structural characteristics of the prototype 3b , that is, highly distorted geometry of the nickel center and intermediate coordination mode of the O O moiety between η¹ and η², are kept in the brominated ligand analogue 3a . The introduction of the electron‐withdrawing substitutents on the distal site of Tp^R affects the thermal stability and reactivity of the nickel(II)‐alkylperoxo species.     

Syntheses,structures and catecholase activities of homo‐ and hetero‐trinuclear cobalt(II) complexes constructed from an acyclic naphthalenediol‐based bis(Salamo)‐type ligand

A series of homo‐ and hetero‐trinuclear cobalt(II) complexes [Co₃(L)(OAc)₂(CH₃CH₂OH)(H₂O)] ( 1 ), [Co₂Ba(L)(OAc)₂] ( 2 ) and [Co₂Ca(L)(OAc)₂]·CHCl₃ ( 3 ), containing an acyclic naphthalenediol‐based ligand H₄L were synthesized. All the three complexes were characterized by elemental analyses, IR, UV – vis spectra and single crystal X‐ray diffraction analyses. Comparative studies of the structures and spectroscopic properties are carried out on these complexes. All of the complexes show catechol oxidase activities in MeCN. Using UV – vis spectroscopy, we monitored the aerial oxidation of 3,5‐di‐tert ‐butylcatechol (3,5‐DTBCH₂) to 3,5‐di‐tert ‐butylquinone (3,5‐DTBQ), which confirms the essential role of these complexes in enhancing the catalytic reaction.     

A mixed‐valence diacetate‐bridged MnII–MnIII complex incorporating a bridging phenolate ligand

The synthesis and characterization of a new unsymmetrical dinucleating N,O‐donor ligand, 2‐[N,N‐bis­(2‐pyridyl­methyl)­amino­methyl]‐6‐[N‐(3,5‐di‐tert‐butyl‐2‐oxidobenzyl)‐N‐(2‐pyridyl­amino)­aminomethyl]‐4‐methyl­phenol (H₂Ldtb), as well as the X‐ray crystal structure of its corresponding mixed‐valence diacetate‐bridged manganese complex, di‐μ‐acetato‐μ‐{2‐[N,N‐bis­(2‐pyridylmethyl)amino­methyl]‐6‐[N‐(3,5‐di‐tert‐butyl‐2‐oxidobenzyl)‐N‐(2‐pyridyl­amino)­aminomethyl]‐4‐methylphenolato}dimanganese(II,III) tetra­phenyl­borate, [Mn^IIMn^III(C₄₂H₄₉N₅O₂)(C₂H₃O₂)₂](C₂₄H₂₀B), are reported. The complex may be regarded as an inter­esting structural model for the mixed‐valence Mn^II–Mn^III state of manganese catalase.     

Synthesis,structural characterization and catalytic activities of dicopper(II) complexes derived from tridentate pyrazole‐based N2O ligands

A group of a diverse family of dinuclear copper(II) complexes derived from pyrazole‐containing tridentate N₂O ligands, 1,3‐bis(3,5‐dimethylpyrazol‐1‐yl)propan‐2‐ol (Hdmpzpo), 1,3‐bis(3‐phenyl‐5‐methyl pyrazol‐1‐yl)propan‐2‐ol (Hpmpzpo) and 1,3‐bis(3‐cumyl‐5‐methylpyrazol‐1‐yl)propan‐2‐ol (Hcmpzpo), were synthesized and characterized by elemental analysis, IR spectroscopy and three of them also by single‐crystal X‐ray diffraction. Three complexes, [Cu₂(pmpzpo)₂](NO₃)₂·2CH₃OH ( 3 ·2CH₃OH), [Cu₂(pmpzpo)₂](ClO₄)₂ ( 4 ) and [Cu₂(cmpzpo)₂](ClO₄)₂·2DMF ( 7 ·2DMF), each exhibits a dimeric structure with a inversion center being located between the two copper atoms. The metal ion is coordinated in a distorted square planar environment by two pyrazole nitrogen atoms and two bridging alkoxo oxygen atoms. Both complexes 1 ·CH₃OH·H₂O and 3 ·2CH₃OH were investigated in anaerobic conditions for the catalytic oxidation of 3,5‐di‐tert‐butylcatechol (3,5‐DTBC) to the corresponding quinone (3,5‐DTBQ), for modeling the functional properties of catechol oxidase. Copyright © 2007 John Wiley & Sons, Ltd.     

Mononuclear Co(III), Ni(II) and Cu(II) complexes of 2‐(2,4‐dichlorobenzamido)‐N'‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)benzohydrazide: Structural insight and biological assay

A series of mononuclear metal complexes of Co(III), Ni(II) and Cu(II) with 2‐(2,4‐dichlorobenzamido)‐N′‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)benzohydrazide ( LH ₃ ) have been synthesized and characterized using various physico‐chemical, spectroscopic and single crystal X‐ray diffraction techniques. Structural studies of [Co( LH )( LH ₂ )]·H₂O ( 4 ) revealed the presence of both amido and imidol tautomeric forms of LH ₃ , resulting in a distorted octahedral geometry around the Co(III) ion. [Ni( LH )(H₂O)]·H₂O ( 5 ) and [Cu( LH )(H₂O)]·H₂O ( 6 ) are isomorphous structures and crystallize in the monoclinic P2₁/c space group. The crystal structures of 4 , 5 and 6 are stabilized by hydrogen bonds formed by the enclathrated water molecules, C‐H···π and π···π interactions. Complexes along with the ligand ( LH ₃ ) were screened for their in vivo anti‐inflammatory activity (carrageenan‐induced rat paw edema method) and in vitro antioxidant activity (DPPH free radical scavenging assay). Metal complexes have shown significant anti‐inflammatory and antioxidant potential.     

Dioxygen Reactivity of Biomimetic Iron–Catecholate and Iron–o‐Aminophenolate Complexes of a Tris(2‐pyridylthio)methanido Ligand: Aromatic C?C Bond Cleavage of Catecholate versus o‐Iminobenzosemiquinonate Radical Formation

An iron(III)–catecholate complex [L¹Fe^III(DBC)] ( 2 ) and an iron(II)–o‐aminophenolate complex [L¹Fe^II(HAP)] ( 3 ; where L¹=tris(2‐pyridylthio)methanido anion, DBC=dianionic 3,5‐di‐tert‐butylcatecholate, and HAP=monoanionic 4,6‐di‐tert‐butyl‐2‐aminophenolate) have been synthesised from an iron(II)–acetonitrile complex [L¹Fe^II(CH₃CN)₂](ClO₄) ( 1 ). Complex 2 reacts with dioxygen to oxidatively cleave the aromatic C? C bond of DBC giving rise to selective extradiol cleavage products. Controlled chemical or electrochemical oxidation of 2 , on the other hand, forms an iron(III)–semiquinone radical complex [L¹Fe^III(SQ)](PF₆) ( 2^ox‐PF₆ ; SQ=3,5‐di‐tert‐butylsemiquinonate). The iron(II)–o‐aminophenolate complex ( 3 ) reacts with dioxygen to afford an iron(III)–o‐iminosemiquinonato radical complex [L¹Fe^III(ISQ)](ClO₄) ( 3^ox‐ClO₄ ; ISQ=4,6‐di‐tert‐butyl‐o‐iminobenzosemiquinonato radical) via an iron(III)–o‐amidophenolate intermediate species. Structural characterisations of 1 , 2 , 2^ox and 3^ox reveal the presence of a strong iron? carbon bonding interaction in all the complexes. The bond parameters of 2^ox and 3^ox clearly establish the radical nature of catecholate‐ and o‐aminophenolate‐derived ligand, respectively. The effect of iron? carbon bonding interaction on the dioxygen reactivity of biomimetic iron–catecholate and iron–o‐aminophenolate complexes is discussed.     

Copper(II) and zinc(II) complexes of pyridine‐2,6‐di­carboxyl­ic acid

The title compounds, bis­(pyridine‐2,6‐di­carboxyl­ato‐N,O,O′)copper(II) monohydrate, [Cu(C₇H₄NO₄)₂]·H₂O, andbis(pyridine‐2,6‐dicarboxylato‐N,O,O′)zinc(II) trihydrate, [Zn(C₇H₄NO₄)₂]·3H₂O, have distorted octahedral geometries about the metal centres. Both metal ions are bonded to four O atoms and two pyridyl‐N atoms from the two terdentate ligand mol­ecules, which are nearly perpendicular to each other. The copper(II) complex has twofold crystallographic symmetry and contains two different ligand mol­ecules, one of which is neutral and another doubly ionized. In contrast, the zinc(II) complex contains two identical singly ionized ligand mol­ecules. Both crystal structures are stabilized by O—H?O intermolecular hydrogen bonds between the complex and the water mol­ecules.     

Two related lithium calixarene complexes, [p‐tert‐butylcalix[4]arene(OMe)(OH)2(OLi)]2·4MeCN and {p‐tert‐butylcalix[4]arene(OH)2(OLi)[OLi(NCMe)2]}2·8MeCN,determined using synchrotron radiation

The crystal structures of acetonitrile solvates of two related lithium calixarene complexes have been determined by low‐temperature single‐crystal X‐ray diffraction using synchrotron radiation. Bis(μ‐5,11,17,23‐tetra‐tert‐butyl‐26,28‐dihydroxy‐25‐methoxy‐27‐oxidocalix[4]arene)dilithium(I) acetonitrile tetrasolvate, [Li₂(C₄₅H₅₇O₄)₂]·4C₂H₃N or [p‐tert‐butylcalix[4]arene(OMe)(OH)₂(OLi)]₂·4MeCN, (I), crystallizes with the complex across a centre of symmetry and with four molecules of unbound acetonitrile of crystallization per complex. Tetraacetonitrilebis(μ‐5,11,17,23‐tetra‐tert‐butyl‐26,28‐dihydroxy‐25,27‐dioxidocalix[4]arene)tetralithium(I) acetonitrile octasolvate, [Li₄(C₄₄H₅₄O₄)₂(C₂H₃N)₄]·8C₂H₃N or {p‐tert‐butylcalix[4]arene(OH)₂(OLi)[OLi(NCMe)₂]}₂·8MeCN, (II), also crystallizes with the complex lying across a centre of symmetry and contains eight molecules of unbound acetonitrile per complex plus four more directly bound to two of the lithium ions, two on each ion. The cores of both complexes are partially supported by O—H...O hydrogen bonds. The methoxy methyl groups in (I) prevent the binding of any more than two Li⁺ ions, while the corresponding two O‐atom sites in (II) bind an extra Li⁺ ion each, making four in total. The calixarene cone adopts an undistorted cone conformation in (I), but an elliptical one in (II).     

5,5′‐Di‐tert‐butyl‐2,2′‐di­hydroxy‐3,3′‐methyl­enedibenz­aldehyde and 6,6′‐di‐tert‐butyl‐8,8′‐methyl­ene­bis­(spiro­[4H‐1,3‐benzodioxin‐2,1′‐cyclo­hexane])

Two related compounds containing p‐tert‐butyl‐o‐methyl­ene‐linked phenol or phenol‐derived subunits are described, namely 5,5′‐di‐tert‐butyl‐2,2′‐di­hydroxy‐3,3′‐methyl­ene­di­benz­aldehyde, C₂₃H₂₈O₄, (I), and 6,6′‐di‐tert‐butyl‐8,8′‐methyl­ene­bis­(spiro­[4H‐1,3‐benzo­di­oxin‐2,1′‐cyclo­hexane]), C₃₅H₄₈O₄, (II). Both compounds adopt a `butterfly' shape, with the two phenol or phenol‐derived O atoms in distal positions. Phenol and aldehyde groups in (I) are involved in intramolecular hydrogen bonds and the two dioxin rings in (II) are in distorted half‐chair conformations.     

Cobalt(II), nickel(II) and copper(II) complexes of iso­quinoline‐3‐carbox­ylate

The crystal structures of the title complexes, namely trans‐bis­(iso­quinoline‐3‐carboxyl­ato‐κ²N,O)­bis­(methanol‐κO)cobalt(II), [Co(C₁₀H₆NO₂)₂(CH₃OH)₂], and the corresponding nickel(II) and copper(II) complexes, [Ni(C₁₀H₆NO₂)₂(CH₃OH)₂] and [Cu(C₁₀H₆NO₂)₂(CH₃OH)₂], are isomorphous and contain metal ions at centres of inversion. The three compounds have the same distorted octahedral coordination geometry, and each metal ion is bonded by two quinoline N atoms, two carboxyl­ate O atoms and two methanol O atoms. Two iso­quinoline‐3‐carboxyl­ate ligands lie in trans positions, forming the equatorial plane, and the two methanol ligands occupy the axial positions. The complex mol­ecules are linked together by O—H⋯O hydrogen bonds between the methanol ligands and neighbouring carboxyl­ate groups.     

Mechanistic Insight into Peroxo‐Shunt Formation of Biomimetic Models for Compound II,Their Reactivity toward Organic Substrates,and the Influence of N‐Methylimidazole Axial Ligation

High‐valent iron‐oxo species have been invoked as reactive intermediates in catalytic cycles of heme and nonheme enzymes. The studies presented herein are devoted to the formation of compound II model complexes, with the application of a water soluble (TMPS)Fe^III(OH) porphyrin ([meso‐tetrakis(2,4,6‐trimethyl‐3‐sulfonatophenyl)porphinato]iron(III) hydroxide) and hydrogen peroxide as oxidant, and their reactivity toward selected organic substrates. The kinetics of the reaction of H₂O₂ with (TMPS)Fe^III(OH) was studied as a function of temperature and pressure. The negative values of the activation entropy and activation volume for the formation of (TMPS)Fe^IV?O(OH) point to the overall associative nature of the process. A pH‐dependence study on the formation of (TMPS)Fe^IV?O(OH) revealed a very high reactivity of OOH^? toward (TMPS)Fe^III(OH) in comparison to H₂O₂. The influence of N‐methylimidazole (N‐MeIm) ligation on both the formation of iron(IV)‐oxo species and their oxidising properties in the reactions with 4‐methoxybenzyl alcohol or 4‐methoxybenzaldehyde, was investigated in detail. Combined experimental and theoretical studies revealed that among the studied complexes, (TMPS)Fe^III(H₂O)(N‐MeIm) is highly reactive toward H₂O₂ to form the iron(IV)‐oxo species, (TMPS)Fe^IV?O(N‐MeIm). The latter species can also be formed in the reaction of (TMPS)Fe^III(N‐MeIm)₂ with H₂O₂ or in the direct reaction of (TMPS)Fe^IV?O(OH) with N‐MeIm. Interestingly, the kinetic studies involving substrate oxidation by (TMPS)Fe^IV?O(OH) and (TMPS)Fe^IV?O(N‐MeIm) do not display a pronounced effect of the N‐MeIm axial ligand on the reactivity of the compound II mimic in comparison to the OH^? substituted analogue. Similarly, DFT computations revealed that the presence of an axial ligand (OH^? or N‐MeIm) in the trans position to the oxo group in the iron(IV)‐oxo species does not significantly affect the activation barriers calculated for C?H dehydrogenation of the selected organic substrates.     

Mononuclear Co(III), Ni(II) and Cu(II) complexes of tridentate di‐tert‐butylphenylhydrazone: Synthesis,characterization, X‐ray crystal structures,Hirshfeld surface analysis,molecular docking and in vivo anti‐inflammatory activity

A new hydrazone (LH₂) derived from the condensation of 2‐(4‐fluorobenzamido)benzohydrazide with 3,5‐di‐tert‐butyl‐2‐hydroxybenzaldehyde was used to synthesize Co(III), Ni(II) and Cu(II) complexes. These were characterized using various physicochemical, thermal, spectroscopic and single‐crystal X‐ray diffraction techniques. All the complexes crystallize in a monoclinic crystal system with P2₁/n space group and Z = 4. Structural studies of [Co(L)(LH)]?H₂O indicate the presence of both amido and imidol tautomeric forms of the ligand, resulting in a distorted octahedral geometry around the Co(III) ion. On the other hand, in the [Ni(L)(DMF)] and [Cu(L)(H₂O)] complexes, the ligand coordinates to the metal through imidol form resulting in distorted square planar geometry, in which the fourth position is occupied by the oxygen of coordinated DMF in [Ni(L)(DMF)] and by a water molecule in [Cu(L)(H₂O)]. Hirshfeld surface calculations were performed to explore hydrogen bonding and C―H???π interactions. Molecular docking studies were carried out to study the interaction between the synthesized compounds and proteins (cyclooxygenase‐2 and 5‐lipoxygenase). The complexes along with the parent ligand were screened for their in vivo anti‐inflammatory activity, using the carrageenan‐induced rat paw oedema method. The complexes show significant anti‐inflammatory potencies.     

Two 2,5‐bis(2‐pyridinyl)‐1,3,4‐oxa­diazo­le–metal complexes (M = Cu and Ni)

The reaction of the diazine ligand 3,5‐bis(2‐pyridinyl)‐1,3,4‐oxa­diazole (pod, C₁₂H₈N₄O), with Cu(CF₃SO₃)₂ or Ni(ClO₄)₂ afforded the title complexes di­aqua­bis­[3,5‐bis(2‐pyridinyl)‐1,3,4‐oxa­diazole‐N²,N³]copper(II) bis­(tri­fluoro­methane­sul­fon­ate), [Cu(pod)₂(H₂O)₂](CF₃SO₃)₂, and di­aqua­bis­[3,5‐bis(2‐pyridinyl)‐1,3,4‐oxa­diazo­le‐N²,N³]­nickel(II) diperchlorate, [Ni(pod)₂(H₂O)₂](ClO₄)₂. Both complexes present a crystallographically centrosymmetric mononuclear cation structure which consists of a six‐coordinated Cu^II or Ni^II ion with two pod mol­ecules acting as bidentate ligands and two axially coordinated water mol­ecules.     

A three‐dimensional supramolecular network built with the zigzag chain complex bis(5‐carboxy‐1H‐imidazole‐4‐carboxyl­ato)copper(II)

In the title complex, poly[copper(II)‐di‐μ‐5‐carboxy‐1H‐imidazole‐4‐carboxyl­ato], [Cu(C₅H₃N₂O₄)₂]_n or [Cu(H₂Imda)₂]_n, each imidazole moiety is bonded to the Cu atom via O and N atoms to give a square‐planar coordination [Cu—O = 2.014 (2) and 2.016 (2) Å, and Cu—N = 1.982 (3) and 1.992 (2) Å]. The distorted square‐pyramidal geometry at the Cu atom results from coordination to an adjacent O atom [Cu—O = 2.305 (2) Å], which generates zigzag chains. There is a sixth, weaker, octahedral coordination to the Cu atom from an inversion‐related O atom [Cu—O = 3.090 (2) Å], which links the chains into sheets in the (100) plane. Imidazole moieties in the sheets are linked in the [100] direction by pairs of N—H⋯O and C—H⋯O hydrogen bonds, thus generating a three‐dimensional network.     

Unusual O‐coordination of caffeine in tetra­kis(μ‐3,5‐dinitro­benzoato‐κ2O:O′)bis­[(caffeine‐κO)copper(II)]

The title compound {systematic name: tetra­kis(μ‐3,5‐dinitro­benzoato‐κ²O:O′)bis­[(3,7‐dihydro‐1,3,7‐trimethyl‐1H‐purine‐2,6‐dione‐κO²)copper(II)]}, [Cu₂(C₇H₃N₂O₆)₄(C₈H₁₀N₄O₂)₂], consists of paddle‐wheel dimeric tetra­kis(μ‐3,5‐dinitro­benzoato‐κ²O:O′)dicopper(II) units with O‐coordinated caffeine mol­ecules in both apical positions. The entire dimeric mol­ecule lies on a tetra­gonal inversion axis, and thus one nitro­benzoate anion with one Cu atom in a special position belong to the independent part of the mol­ecule. The caffeine ligand bonded to the Cu atom is disordered on a local twofold non‐crystallographic axis coincident with the axis. A π–π stacking inter­action is observed between the caffeine rings and adjacent symmetry‐related benzene rings of the 3,5‐dinitro­benzoate anions.     

2H‐Tetrakis(3,5‐di‐tert‐butyl)phenylporphyrin on a Cu(110) Surface: Room‐Temperature Self‐Metalation and Surface‐Reconstruction‐Facilitated Self‐Assembly

The adsorption behavior of 2H‐tetrakis(3,5‐di‐tert‐butyl)phenylporphyrin (2HTTBPP) on Cu(110) and Cu(110)–(2×1)O surfaces have been investigated by using variable‐temperature scanning tunneling microscopy (STM) under ultrahigh vacuum conditions. On the bare Cu(110) surface, individual 2HTTBPP molecules are observed. These molecules are immobilized on the surface with a particular orientation with respect to the crystallographic directions of the Cu(110) surface and do not form supramolecular aggregates up to full monolayer coverage. In contrast, a chiral supramolecular structure is formed on the Cu(110)–(2×1)O surface, which is stabilized by van der Waals interactions between the tert‐butyl groups of neighboring molecules. These findings are explained by weakened molecule–substrate interactions on the Cu(110)–(2×1)O surface relative to the bare Cu(110) surface. By comparison with the corresponding results of Cu–tetrakis(3,5‐di‐tert‐butyl)phenylporphyrin (CuTTBPP) on Cu(110) and Cu(110)–(2×1)O surfaces, we find that the 2HTTBPP molecules can self‐metalate on both surfaces with copper atoms from the substrate at room temperature (RT). The possible origins of the self‐metalation reaction at RT are discussed. Finally, peculiar irreversible temperature‐dependent switching of the intramolecular conformations of the investigated molecules on the Cu(110) surface was observed and interpreted.