The properties of paddlewheel diruthenium compounds significantly depend on the nature of the bridging equatorial ligands.The charge of these complexes is a factor to take into account when studying their interaction ...The properties of paddlewheel diruthenium compounds significantly depend on the nature of the bridging equatorial ligands.The charge of these complexes is a factor to take into account when studying their interaction with proteins.To compare the reactivity of diruthenium compounds with the model protein hen egg white lysozyme(HEWL),we have prepared the well-known anionic complex[Ru_(2)(CO_(3))4]3−,two new anionic species,[Ru_(2)(D-p-FPhF)(CO_(3))3]^(2−)and[Ru_(2)(DAniF)(CO_(3))3]^(2−),and their analogues[Ru_(2)Cl(D-p-FPhF)(O_(2)CCH_(3))3]and[Ru_(2)Cl(DAniF)(O_(2)CCH_(3))3]that generate cationic species in solution(D-p-FPhF−=N,N’-bis(4-fluorophenyl)formamidinate and DAniF−=N,N’-bis(4-methoxyphenyl)formamidinate).The interaction of these compounds with HEWL was investigated by UV-vis absorption spectroscopy,circular dichroism,intrinsic fluorescence and X-ray crystallography.The molecular structures of the adducts differ in the number of metal binding sites,in the binding mode and in the type of fragments that are bound to the protein.The charge of the diruthenium complexes in aqueous solutions strongly influences their protein binding properties.High-negative charge complexes are non-covalently bound.However,the replacement of carbonate ligands changes the negative charge of these complexes and favours covalent binding.These results have great implications for further studies in the tailoring of artificial diruthenium-containing metalloenzymes.展开更多
The controlled release of biologically active species from diruthenium compounds is crucial for the devel-opment of selective drug delivery systems based on such complexes,which in addition display antineo-plastic pro...The controlled release of biologically active species from diruthenium compounds is crucial for the devel-opment of selective drug delivery systems based on such complexes,which in addition display antineo-plastic properties by themselves.In the present work,we analyse in detail the kinetics of the pH-triggered release of the auxin-related hormones 2,4-D(2,4-dichlorophenoxyacetate)and NAA(1-naphthaleneace-tate)from the metal–metal bonded tris(formamidinato)Ru_(2)^(5+)complexes[Ru_(2)Cl(μ-DPhF)_(3)(μ-2,4-D)](Ru_(2),4-D),[Ru_(2)Cl(μ-DPhF)_(3)(μ-NAA)](RuNAA),[Ru_(2)Cl(μ-DAniF)_(3)(μ-2,4-D)](Ru’2,4-D)and[Ru_(2)Cl(μ-DAniF)_(3)(μ-NAA)](Ru’NAA)(DPhF=N,N’-diphenylformamidinate,DAniF=N,N’-bis(p-methoxy)phenylfor-mamidinate).Moreover,the synthesis and complete characterisation of[Ru_(2)Cl(μ-DAniF)_(3)(μ-IAA)](Ru’IAA,IAA=indole-3-acetate),Ru’2,4-D and Ru’NAA,including the crystal structure of the two latter ones,is reported.The release of auxins is studied through a fluorimetric quantitative assay,which allows deter-mining the influence of different formamidinate ancillary ligands and the nature of the outgoing auxin ligand in the release process.Chemometrics is employed to evaluate the statistical significance of the variables.The release of auxins is slower at physiological pH and occurs faster at slightly acidic pH values.Compounds containing DPhF ancillary ligands and NAA outgoing ligand present a slower dissociation of the auxin,which is not complete in the first 24 h.The release rate is also correlated with the bond dis-tance O1(auxin)–Ru1(hexacoordinated).A mechanism of the substitution reaction is tentatively proposed based on these findings.Overall,these results pave the way towards new systems for the controlled deliv-ery of antineoplastic drugs under mild-acidic conditions like those surrounding solid tumours.展开更多
Correction for‘Synthesis and studies of aqueous-stable diruthenium aminocarbyne complexes uncovered an N-indolyl derivative as a prospective anticancer agent’by Matteo Fiaschi et al.,Inorg.Chem.Front.,2024,11,2841-2...Correction for‘Synthesis and studies of aqueous-stable diruthenium aminocarbyne complexes uncovered an N-indolyl derivative as a prospective anticancer agent’by Matteo Fiaschi et al.,Inorg.Chem.Front.,2024,11,2841-2862,https://doi.org/10.1039/D4QI00096J.展开更多
We conducted a systematic study on the reactivity of[Ru_(2)Cp_(2)(CO)4](Cp=η^(5)-C_(5)H_(5))with isocyanides and the subsequent methylation reaction to produce[Ru_(2)Cp_(2)(CO)2(μ-CO){μ-CNMe(R)}]^(+)complexes as CF...We conducted a systematic study on the reactivity of[Ru_(2)Cp_(2)(CO)4](Cp=η^(5)-C_(5)H_(5))with isocyanides and the subsequent methylation reaction to produce[Ru_(2)Cp_(2)(CO)2(μ-CO){μ-CNMe(R)}]^(+)complexes as CF_(3)SO_(3)^(−)salts,[2a-h]^(+)[R=Me,cyclohexyl(Cy),2,6-C_(6)H_(3)Me_(2)(Xyl),1H-indol-5-yl,2-naphthyl,4-C_(6)H_(4)OMe,(S)-CHMe(Ph),CH_(2)Ph(Bn)].The resulting products,including five novel ones,underwent structural characterization by IR and multinuclear NMR spectroscopy,with five of them further confirmed via single crystal X-ray diffraction.Compounds[2a-e,h]CF_(3)SO_(3)exhibit appreciable water solubility,substantial amphiphilic character and out-standing stability in physiological-like solutions(negligible degradation after 72 hours in DMEM at 37℃).Representative complexes[2b]^(+)and[2c]^(+)were additionally characterized through cyclic voltammetry in CH_(2)Cl_(2)and in aqueous phosphate buffer solution.Compounds[2a-d]CF_(3)SO_(3)were assessed for in vitro cyto-toxicity against A2780,A2080R and MCF-7 human cancer cell lines,and[2a-c]CF_(3)SO_(3)revealed significant-to-moderate cytotoxicity,outperforming cisplatin in several cases.The most favourable IC_(50)values were observed for[2d]CF_(3)SO_(3),ranging from 3.7 to 13.0μM.Experiments on the noncancerous human cell line MRC-5 highlighted a reasonable selectivity for[2b-d]CF_(3)SO_(3),with the highest selectivity indexes(SI)calcu-lated as 10.1(ratio of IC_(50)on MRC-5/IC_(50)on A2780)and 8.5(ratio of IC_(50)on MRC-5/IC_(50)on A2780R)for[2d]CF_(3)SO_(3).Subsequently,[2d]CF_(3)SO_(3)was tested across a panel of HOS,A549,PANC1,CaCo2,PC3 and HeLa cancer cells,showing variable cytotoxicity with IC_(50)values in the range of 9.7 to 20.3μM.The cellular effects of[2d]^(+)on A2780 cells were investigated using flow cytometry assays,focusing on the cell cycle modification,time-resolved cellular uptake,intracellular ROS production,mitochondrial membrane depolarization,induction of cell death through apoptosis,activation of caspases 3/7 and induction of autophagy.Overall,the results suggest a diphasic mechanism of action for[2d]^(+),inducing metabolic stress and arresting proliferation in the first/fast phase,followed by the induction of apoptosis and autophagy in the second/slower phase.展开更多
Metastasis is a major health threat for most cancer patients,thus anti-metastasis treatments that reduce cell migration and invasion are critical for cancer treatment. In this study,four anthraquinone-bridged diruthen...Metastasis is a major health threat for most cancer patients,thus anti-metastasis treatments that reduce cell migration and invasion are critical for cancer treatment. In this study,four anthraquinone-bridged diruthenium(Ⅱ) complexes,[(bpy)_(2)Ru(L)Ru(bpy)_(2)]^(4+) (Ru1,L=1,4-bis(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)anthracene-9,10-dione;Ru2,L=1,5-bis(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)anthracene-9,10-dione;Ru3,L=2,6-bis(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)anthracene-9,10-dione;and Ru4,L=2,7-bis(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)anthracene-9,10-dione) were synthesized and characterized. These Ru(Ⅱ) complexes exhibited multi-targeted anti-metastatic properties against human hepatocarcinoma MHCC97-H cells that included the inhibition of migration and invasion. Further investigation of the intracellular mechanisms revealed that Ru(Ⅱ) complexes suppressed the phosphorylation of ERK and AKT. Moreover,significant reduction of the extracellular and intracellular expression of the metastatic regulatory proteins MMP-2 and MMP-9 was also observed after Ru1–Ru4 treatment. In addition,these Ru(Ⅱ) complexes negatively modulate the actin cytoskeleton by inhibiting Cdc42 protein expression,arresting the cells in the G2/M phase. The results indicate that these ruthenium(Ⅱ) complexes have potential as drug candidates for anti-metastatic therapies.展开更多
This article provides an overview of the application of diruthenium(Ⅱ,Ⅲ)paddlewheel complexes for anticancer purposes.The use of this coordinative construct is indeed attractive because it provides an excellent oppo...This article provides an overview of the application of diruthenium(Ⅱ,Ⅲ)paddlewheel complexes for anticancer purposes.The use of this coordinative construct is indeed attractive because it provides an excellent opportunity to combine the pharmacological properties of the dimetallic ruthenium center with those derived from the specific choice of ligands bearing a carboxylic function capable of coordination towards the Ru-Ru core.展开更多
A new facile strategy has been reported for the synthesis of homovalent diruthenium(Ⅲ,Ⅲ) phosphates. On assembling the homovalent Ru_(2) units and Cu^(2+) in the presence of K^(+),new trimetallic phosphates,K_(2)[{C...A new facile strategy has been reported for the synthesis of homovalent diruthenium(Ⅲ,Ⅲ) phosphates. On assembling the homovalent Ru_(2) units and Cu^(2+) in the presence of K^(+),new trimetallic phosphates,K_(2)[{Cu(H_(2)O)}_(2)Ru_(2)(PO_(4))_(4)(H_(2)O)_(2)] (1),were formed. In compound 1,the Ru_(2) dimer showed a Ru–Ru double bond distance of 2.3400 Å with a high spin ground state S=2,and neighboring [Ru_(2)(PO_(4))_(4)(H_(2)O)_(2)]^(6−) units were linked via distorted tetragonal pyramid Cu(H_(2)O)^(2+) ions,forming the negative layer [{Cu(H_(2)O)}_(2)Ru_(2)(PO_(4))_(4)(H_(2)O)_(2)]_(n)^(2n−). Antiferromagnetic coupling was mediated between Ru_(2)^(6+) and Cu^(2+) via O–P–O bridges. Detailed magnetism measurements demonstrated that compound 1 exhibited a two-step relaxation in oscillation susceptibilities,and an order below 14 K with a large coercive field of H_(c)=24.9 kOe at 1.8 K. It is the highest Tc and Hc for the non-carboxylate diruthenium compounds reported to date.展开更多
A cyclometalated diruthenium complex 2 bridged by 1,2,4,5-tetra(pyrid-2-yl)benzene with six carboxylic acid groups at two ends was synthesized.Monolayer and multilayer films FTO/TiO2/(2)n(Zr)(n=1,2)and FTO/SnO2:Sb/(2)...A cyclometalated diruthenium complex 2 bridged by 1,2,4,5-tetra(pyrid-2-yl)benzene with six carboxylic acid groups at two ends was synthesized.Monolayer and multilayer films FTO/TiO2/(2)n(Zr)(n=1,2)and FTO/SnO2:Sb/(2)n(Zr)(n=1-4)have been prepared via interfacial layer-by-layer coordination assembly of 2 with zirconium(IV)ions.All films show two consecutive redox couples in the potential range between 0 and+1.0 V vs.Ag/AgCl.These films exhibit reversible near-infrared electrochromism upon switching of redox potential.The response time of the films on SnO2:Sb is around a few seconds,while that on TiO2 is around a few tens of seconds.The film deposition cycles were found to have a great impact on the electrochromic performance.Among six films examined,the two-layered film on SnO2:Sb displays the best balanced performance with a contrast ratio of 56%at 1,150 nm and good cyclic stability(9%loss of contrast ratio after 1,000 continuous double-potential-switching cycles),which is superior to that of the previously reported electropolymerized films of a related diruthenium complex with the same bridging ligand.In addition,the X-ray photoelectron spectroscopy,scanning electron microscopy,and electron transfer mechanism of these films have been investigated.展开更多
基金Comunidad de Madrid(Project S2017/BMD-3770-CM)Universidad Complutense de Madrid(Program PR3/23)are gratefully acknowledged for the financial support+2 种基金A.T.also acknowledges the Universidad Complutense for a Predoctoral Grant(CT63/19-CT64/19)Research Stay Grant(EB25/22)the Spanish Ministry of Science and Innovation for a Postgraduate Fellowship at Residencia de Estudiantes(2021–2022).
文摘The properties of paddlewheel diruthenium compounds significantly depend on the nature of the bridging equatorial ligands.The charge of these complexes is a factor to take into account when studying their interaction with proteins.To compare the reactivity of diruthenium compounds with the model protein hen egg white lysozyme(HEWL),we have prepared the well-known anionic complex[Ru_(2)(CO_(3))4]3−,two new anionic species,[Ru_(2)(D-p-FPhF)(CO_(3))3]^(2−)and[Ru_(2)(DAniF)(CO_(3))3]^(2−),and their analogues[Ru_(2)Cl(D-p-FPhF)(O_(2)CCH_(3))3]and[Ru_(2)Cl(DAniF)(O_(2)CCH_(3))3]that generate cationic species in solution(D-p-FPhF−=N,N’-bis(4-fluorophenyl)formamidinate and DAniF−=N,N’-bis(4-methoxyphenyl)formamidinate).The interaction of these compounds with HEWL was investigated by UV-vis absorption spectroscopy,circular dichroism,intrinsic fluorescence and X-ray crystallography.The molecular structures of the adducts differ in the number of metal binding sites,in the binding mode and in the type of fragments that are bound to the protein.The charge of the diruthenium complexes in aqueous solutions strongly influences their protein binding properties.High-negative charge complexes are non-covalently bound.However,the replacement of carbonate ligands changes the negative charge of these complexes and favours covalent binding.These results have great implications for further studies in the tailoring of artificial diruthenium-containing metalloenzymes.
基金funded by Comunidad de Madrid(B2017/BMD-3770-CM)to S.H.the Spanish Ministry of Science and Innovation(RTI2018-094793-B-I00)to C.G.+1 种基金by institutional grants from Fundación Ramón Areces and Banco de Santander to the Centro de Biología Molecular Severo OchoaI.C.acknowl-edges a predoctoral grant(CT82/20-CT83/20)from Complutense University of Madrid and Banco de Santander.
文摘The controlled release of biologically active species from diruthenium compounds is crucial for the devel-opment of selective drug delivery systems based on such complexes,which in addition display antineo-plastic properties by themselves.In the present work,we analyse in detail the kinetics of the pH-triggered release of the auxin-related hormones 2,4-D(2,4-dichlorophenoxyacetate)and NAA(1-naphthaleneace-tate)from the metal–metal bonded tris(formamidinato)Ru_(2)^(5+)complexes[Ru_(2)Cl(μ-DPhF)_(3)(μ-2,4-D)](Ru_(2),4-D),[Ru_(2)Cl(μ-DPhF)_(3)(μ-NAA)](RuNAA),[Ru_(2)Cl(μ-DAniF)_(3)(μ-2,4-D)](Ru’2,4-D)and[Ru_(2)Cl(μ-DAniF)_(3)(μ-NAA)](Ru’NAA)(DPhF=N,N’-diphenylformamidinate,DAniF=N,N’-bis(p-methoxy)phenylfor-mamidinate).Moreover,the synthesis and complete characterisation of[Ru_(2)Cl(μ-DAniF)_(3)(μ-IAA)](Ru’IAA,IAA=indole-3-acetate),Ru’2,4-D and Ru’NAA,including the crystal structure of the two latter ones,is reported.The release of auxins is studied through a fluorimetric quantitative assay,which allows deter-mining the influence of different formamidinate ancillary ligands and the nature of the outgoing auxin ligand in the release process.Chemometrics is employed to evaluate the statistical significance of the variables.The release of auxins is slower at physiological pH and occurs faster at slightly acidic pH values.Compounds containing DPhF ancillary ligands and NAA outgoing ligand present a slower dissociation of the auxin,which is not complete in the first 24 h.The release rate is also correlated with the bond dis-tance O1(auxin)–Ru1(hexacoordinated).A mechanism of the substitution reaction is tentatively proposed based on these findings.Overall,these results pave the way towards new systems for the controlled deliv-ery of antineoplastic drugs under mild-acidic conditions like those surrounding solid tumours.
文摘Correction for‘Synthesis and studies of aqueous-stable diruthenium aminocarbyne complexes uncovered an N-indolyl derivative as a prospective anticancer agent’by Matteo Fiaschi et al.,Inorg.Chem.Front.,2024,11,2841-2862,https://doi.org/10.1039/D4QI00096J.
基金L.B.,T.F.and F.M.thank the University of Pisa(Fondi di Ateneo 2020 and PRA_2020_39)for financial supportJ.V.,T.M.and Z.T.acknowledge the financial support from the ERDF/ESF Project Nanotechnologies for Future(CZ.02.1.01/0.0/0.0/16_019/0000754)thank Ms Marta Rešováfor help with biological testing,Prof.MarekŠebela for assistance with MALDI-TOF MS experiments,and Dr Ondřej Vrobel for assist-ance with some of the mass spectrometry experiments。
文摘We conducted a systematic study on the reactivity of[Ru_(2)Cp_(2)(CO)4](Cp=η^(5)-C_(5)H_(5))with isocyanides and the subsequent methylation reaction to produce[Ru_(2)Cp_(2)(CO)2(μ-CO){μ-CNMe(R)}]^(+)complexes as CF_(3)SO_(3)^(−)salts,[2a-h]^(+)[R=Me,cyclohexyl(Cy),2,6-C_(6)H_(3)Me_(2)(Xyl),1H-indol-5-yl,2-naphthyl,4-C_(6)H_(4)OMe,(S)-CHMe(Ph),CH_(2)Ph(Bn)].The resulting products,including five novel ones,underwent structural characterization by IR and multinuclear NMR spectroscopy,with five of them further confirmed via single crystal X-ray diffraction.Compounds[2a-e,h]CF_(3)SO_(3)exhibit appreciable water solubility,substantial amphiphilic character and out-standing stability in physiological-like solutions(negligible degradation after 72 hours in DMEM at 37℃).Representative complexes[2b]^(+)and[2c]^(+)were additionally characterized through cyclic voltammetry in CH_(2)Cl_(2)and in aqueous phosphate buffer solution.Compounds[2a-d]CF_(3)SO_(3)were assessed for in vitro cyto-toxicity against A2780,A2080R and MCF-7 human cancer cell lines,and[2a-c]CF_(3)SO_(3)revealed significant-to-moderate cytotoxicity,outperforming cisplatin in several cases.The most favourable IC_(50)values were observed for[2d]CF_(3)SO_(3),ranging from 3.7 to 13.0μM.Experiments on the noncancerous human cell line MRC-5 highlighted a reasonable selectivity for[2b-d]CF_(3)SO_(3),with the highest selectivity indexes(SI)calcu-lated as 10.1(ratio of IC_(50)on MRC-5/IC_(50)on A2780)and 8.5(ratio of IC_(50)on MRC-5/IC_(50)on A2780R)for[2d]CF_(3)SO_(3).Subsequently,[2d]CF_(3)SO_(3)was tested across a panel of HOS,A549,PANC1,CaCo2,PC3 and HeLa cancer cells,showing variable cytotoxicity with IC_(50)values in the range of 9.7 to 20.3μM.The cellular effects of[2d]^(+)on A2780 cells were investigated using flow cytometry assays,focusing on the cell cycle modification,time-resolved cellular uptake,intracellular ROS production,mitochondrial membrane depolarization,induction of cell death through apoptosis,activation of caspases 3/7 and induction of autophagy.Overall,the results suggest a diphasic mechanism of action for[2d]^(+),inducing metabolic stress and arresting proliferation in the first/fast phase,followed by the induction of apoptosis and autophagy in the second/slower phase.
基金supported by the 973 Program(no.2015CB856301)the National Science Foundation of China(no.21471164 and 21525105)+2 种基金Guangdong Province Public Research and Capacity-Building of Special Foundation(no.2015A020211037)Guangzhou Science and Technology Project(no.201607010087)the Natural Science Foundation of Guangdong Province(no.2016A030310298).
文摘Metastasis is a major health threat for most cancer patients,thus anti-metastasis treatments that reduce cell migration and invasion are critical for cancer treatment. In this study,four anthraquinone-bridged diruthenium(Ⅱ) complexes,[(bpy)_(2)Ru(L)Ru(bpy)_(2)]^(4+) (Ru1,L=1,4-bis(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)anthracene-9,10-dione;Ru2,L=1,5-bis(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)anthracene-9,10-dione;Ru3,L=2,6-bis(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)anthracene-9,10-dione;and Ru4,L=2,7-bis(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)anthracene-9,10-dione) were synthesized and characterized. These Ru(Ⅱ) complexes exhibited multi-targeted anti-metastatic properties against human hepatocarcinoma MHCC97-H cells that included the inhibition of migration and invasion. Further investigation of the intracellular mechanisms revealed that Ru(Ⅱ) complexes suppressed the phosphorylation of ERK and AKT. Moreover,significant reduction of the extracellular and intracellular expression of the metastatic regulatory proteins MMP-2 and MMP-9 was also observed after Ru1–Ru4 treatment. In addition,these Ru(Ⅱ) complexes negatively modulate the actin cytoskeleton by inhibiting Cdc42 protein expression,arresting the cells in the G2/M phase. The results indicate that these ruthenium(Ⅱ) complexes have potential as drug candidates for anti-metastatic therapies.
基金support of the Italian Ministry of Research(MUR).
文摘This article provides an overview of the application of diruthenium(Ⅱ,Ⅲ)paddlewheel complexes for anticancer purposes.The use of this coordinative construct is indeed attractive because it provides an excellent opportunity to combine the pharmacological properties of the dimetallic ruthenium center with those derived from the specific choice of ligands bearing a carboxylic function capable of coordination towards the Ru-Ru core.
基金support received from the National Natural Science Foundation of China(no.21673172 and 21501141)the Natural Science Foundation of Shaanxi Province(no.2015JM2054)the Education Commission of Shaanxi Province(no.2014JQ6223 and 14JS092).
文摘A new facile strategy has been reported for the synthesis of homovalent diruthenium(Ⅲ,Ⅲ) phosphates. On assembling the homovalent Ru_(2) units and Cu^(2+) in the presence of K^(+),new trimetallic phosphates,K_(2)[{Cu(H_(2)O)}_(2)Ru_(2)(PO_(4))_(4)(H_(2)O)_(2)] (1),were formed. In compound 1,the Ru_(2) dimer showed a Ru–Ru double bond distance of 2.3400 Å with a high spin ground state S=2,and neighboring [Ru_(2)(PO_(4))_(4)(H_(2)O)_(2)]^(6−) units were linked via distorted tetragonal pyramid Cu(H_(2)O)^(2+) ions,forming the negative layer [{Cu(H_(2)O)}_(2)Ru_(2)(PO_(4))_(4)(H_(2)O)_(2)]_(n)^(2n−). Antiferromagnetic coupling was mediated between Ru_(2)^(6+) and Cu^(2+) via O–P–O bridges. Detailed magnetism measurements demonstrated that compound 1 exhibited a two-step relaxation in oscillation susceptibilities,and an order below 14 K with a large coercive field of H_(c)=24.9 kOe at 1.8 K. It is the highest Tc and Hc for the non-carboxylate diruthenium compounds reported to date.
基金supported by the National Natural Science Foundation of China (21872154), Beijing National Science Foundation (2191003)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB12010400)
文摘A cyclometalated diruthenium complex 2 bridged by 1,2,4,5-tetra(pyrid-2-yl)benzene with six carboxylic acid groups at two ends was synthesized.Monolayer and multilayer films FTO/TiO2/(2)n(Zr)(n=1,2)and FTO/SnO2:Sb/(2)n(Zr)(n=1-4)have been prepared via interfacial layer-by-layer coordination assembly of 2 with zirconium(IV)ions.All films show two consecutive redox couples in the potential range between 0 and+1.0 V vs.Ag/AgCl.These films exhibit reversible near-infrared electrochromism upon switching of redox potential.The response time of the films on SnO2:Sb is around a few seconds,while that on TiO2 is around a few tens of seconds.The film deposition cycles were found to have a great impact on the electrochromic performance.Among six films examined,the two-layered film on SnO2:Sb displays the best balanced performance with a contrast ratio of 56%at 1,150 nm and good cyclic stability(9%loss of contrast ratio after 1,000 continuous double-potential-switching cycles),which is superior to that of the previously reported electropolymerized films of a related diruthenium complex with the same bridging ligand.In addition,the X-ray photoelectron spectroscopy,scanning electron microscopy,and electron transfer mechanism of these films have been investigated.
