An Unprecedented Bird Nest Molybdenum(V) Cobalto-Phosphate Nanosized Wheel Constructed from the [H55 (Mo24 O48 )(Co4 O)2 Co16 (PO4 )42 (py)6 (EtOH)2 (H2 O)11 ]3- Anion.

An unprecedented bird-nest high-nuclear molybdenum(V) cobalto-phosphate nanosized wheel modified by imidazole (im) and pyridine (py), {[H55 (Mo24 O48 )(Co4 O)2 Co16 (PO4 )42 (py)6 (EtOH)2 (H2 O)11 ]- @[(Him)2 (Hpy)]}(N-Et-py)(H2 PO4 )(py)7 (EtOH)⋅12 H2 O (1), has been successfully synthesized by self-assembly. The anionic huge wheel consists of two rare {Co4 O} squares, four {Co4 } tetramers, four {Mo4 } tetramers and four {Mo2 } dimers, linked by bridging oxygen atoms and [PO4 ] groups and encloses two imidazolium cations and a protonated pyridium for charge balance. Surprisingly, 1 represents the first twisted wheel-shaped cluster with a record high-nuclear molybdenum(V) cobalto-phosphate. The delocalized electron effects of the cluster are enhanced with the help of coordinated py ligands, which endows 1 with an excellent third-order nonlinear optical (NLO) response. Additionally, 1 also shows a better photocatalytic water oxidation activity than Co(NO3 )2 with the O2 production of 205 µmol during 6 h in the absence of the [Ru(bpy)3 ]2+ photosensitizer.

Two 2D Layered P4Mo6 Clusters with Potential Bifunctional Properties: Proton Conduction and CO2 Photoreduction.

Two hourglass-type molybdophosphate hybrids with the formulas [Cd(H2O)2DABT]4[Cd(H7P4Mo6O31)2]·19H2O (1) and (C2H5OH)(C3H5N2)6[Co3(H6P4Mo6O31)2]·H2O (2) (DABT= 3,3'-diamino-5,5'-bis(1H-1,2,4-triazole)) have been successfully designed and synthesized via a hydrothermal method. Structure analysis revealed that the inorganic moieties in compounds 1 and 2 are made up of hourglass-type {M[P4Mo6]2} (M = Cd/Co) structure, which were constructed by two (P4Mo6) units with single transition metal (TM) (Cd/Co) atom as the central metal. The {M[P4Mo6]2} (M = Cd/Co) structures were then further connected by TM to constitute a 2D layered structure. Surprisingly, under the condition of 60 °C and 98% RH, compounds 1 and 2 exhibited excellent proton conductivity of 1.35 × 10-3 and 3.78 × 10-3 S cm-1, respectively. Furthermore, compound 2 can act as heterogeneous catalyst for CO2 photoreduction, which indicates that it may be a bifunctional POM-based material with great promise.

Lewis Acid Dominant Windmill-Shaped V8 Clusters: A Bifunctional Heterogeneous Catalyst for CO2 Cycloaddition and Oxidation of Sulfides.

Carbon dioxide (CO2) and sulfides in gasoline are the main causes of air pollution. Considerable attention has been devoted to solving the problems, and the catalytic reaction seems to be a good choice. Owing to the high density of Lewis acid (LA) active sites and large numbers of open methoxide groups, polyoxovanadates (POVs) are an undisputed option as a heterogeneous catalyst for the CO2 cycloaddition reaction and catalytic oxidation of sulfides. On the basis of the above, a series of V8 clusters, [(C2N2H8)4(CH3O)8VIV8O12]·CH3OH (V8-1a), [(C2N2H8)4(CH3O)4VIV4VV4O16]·4CH3OH (V8-1), [(C3N2H10)4(CH3O)4VIV4VV4O16]·5H2O (V8-2), [(C6N2H14)4(CH3O)4VIV4VV4O16]·5CH3OH·2H2O (V8-3), have been legitimately designed and triumphantly isolated. In the synthesis process, three different kinds of Lewis bases (LBs), ethanediamine, 1,2-diaminopropane, and 1,2-cyclohexanediamine, were used to modify LA {V8} clusters to form four diverting windmill-shaped configuration. Among them, the vanadium atoms in V8-1a are +4 valence of VIV, while the vanadium atoms in V8-1-3 are mixed valence states of VIV and VV. Magnetic property investigation indicates that the antiferromagnetic coupling interactions between VIV ions all exist in the four compounds. The compound V8-1 also demonstrated high catalytic activity in the cycloaddition of CO2 to several epoxides under relatively mild conditions (70 °C, 0.5 MPa). More importantly, the reaction pressure 0.5 MPa is the lowest among the high nuclear polyoxometallates (POMs). Furthermore, V8-1 also has an excellent catalytic conversion for the oxidation of sulfides. The catalytic tests manifested that V8-1 was a very efficient difunctional heterogeneous catalyst for CO2 cycloaddition reaction and catalytic oxidation of sulfides.

Cl--Templated Assembly of Novel Peanut-like Ln40Ni44 Heterometallic Clusters Exhibiting a Large Magnetocaloric Effect.

Two novel and fascinating high-nuclearity lanthanide-transition (4f-3d) heterometallic clusters were obtained based on an anion-template (Cl-) and ligand-controlled approach, formulated as [Gd40Ni44(CO3)12(CH3COO)4(IDA)44(C2O4)(µ2-O)4(µ3-OH)60(µ3-O)6(H2O)12]·Cl10·20H2O (abbreviated as Gd40Ni44, 1) and [Eu40Ni44(CO3)12(CH3COO)6(IDA)44(C2O4)(µ2-O)4(µ3-OH)62(µ3-O)4(H2O)12]·Cl10·23H2O (abbreviated as Eu40Ni44, 2), where H2IDA = iminodiacetic acid and H2C2O4 = oxalic acid. Structural analysis exhibits that the compounds 1 and 2 were both constructed by two enticing bowl-like anion units Ln20Ni22, featuring peanut-like structures. Besides, the assembly of Ln20Ni22 was templated by five Cl- ions. Magnetically, compound 1 shows a significant magnetocaloric effect, with -ΔSm = 36.05 J kg-1 K-1 at 3 K for ΔH = 7 T.

Multifunctional Polymolybdate-Based Metal-Organic Framework as an Efficient Catalyst for the CO2 Cycloaddition and as the Anode of a Lithium-Ion Battery.

A three-dimensional polymolybdate-based metal-organic framework (POMOF) consisting of Zn-ε-Keggin unit and organic linker, {[PMo8VMo4VIO37(OH)3Zn4][BPE]2}·[BPE] (1), was successfully obtained by the hydrothermal method. Compound 1 is composed of Zn-ε-Keggin units and BPE ligands, featuring a fascinating 5-fold interpenetrating framework with dia topology. The catalytic performance of compound 1 was investigated, and experiments showed that 1 could effectively facilitate the cycloaddition reaction of CO2 with epoxides as Lewis acid heterogeneous catalyst. Moreover, compound 1 also was studied as LIBs anode material, and it showed reversible capacity of 546 mA h g-1 at 100th cycle.

Exploring the Magnetic Interaction of Asymmetric Structures Based on Chiral VIII8 Clusters.

Polyoxovanadates (III) are important class of polyoxometalates in molecular magnetism field, and particularly the systems which contain vanadium(III) centers. To date, only very few highly reduced vanadium polynuclear complexes were reported, which remains a significant challenge to synthesize novel polyoxovanadates, owing to the characteristics of easily oxidized vanadium(III). Herein, two unprecedented petaloid chiral octanuclear polyoxovanadates, l- and d-[H2N(CH3)2]12.5(H3N(CH2)2NH3)(H3O)1.5(VIIIµ2-OH)8(SO4)16·2H2O (L-, D-V8), have been successfully obtained by solvothermal method without any chiral auxiliary. Both L- and D-V8 compounds contain the motif eight-membered ring (Vµ2-O)8(SO4)16 constituted of three different chiral entangled loops with the V atoms as nodes. Bond valence calculation (BVC) analysis indicates that all the V ions existed in L, D-V8 are +3 value. The magnetic behavior of compounds indicated ferromagnetic coupling between vanadium(III) ions. To our knowledge, it is the first chiral highly reduced polyoxovanadates that exhibit excellent ferromagnetism.

Polyoxometalate-Based Well-Defined Rodlike Structural Multifunctional Materials: Synthesis, Structure, and Properties.

The unpredictability of the polyoxometalate (POM) coordination model and the diversity of organic ligands provide more possibilities for the exploration and fabrication of various novel POM-based materials. In this work, a series of POM-based lanthanide (Ln)-Schiff base nanoclusters, [Ln(H2O)2(DAPSC)]2[Ln(H2O)3(DAPSC)]2[(SiW12O40)]3·15H2O (Ln = Sm, 1; Eu, 2; Tb, 3), have been successfully isolated by the reaction of classical Keggin POMs, a Ln3+ ion, and a Schiff-base ligand [2,6-diacetylpyridine bis(semicarbazone), abbreviated as DAPSC]. Both the hindrance effect of the organic ligand and charge balance endow the cluster with fascinating structural features of discrete and linear arrangement. The title compounds with dimensions of ca. 4 × 1 × 1 nm3 are first trimeric polyoxometalate-based nanosized compounds, constructed by saturated POM anions (SiW12O404-, denoted as SiW12). Moreover, the properties (stability, electrochemistry, third-order nonlinear optics, and magnetism) of the compounds have also been studied.

Exploring the Performance Improvement of Magnetocaloric Effect Based Gd-Exclusive Cluster Gd60.

Despite wide potential applications of Gd-clusters in magnetocaloric effect (MCE) owing to f7 electron configuration of Gd(III), the structural improvement in order to enhance MCE remains difficult. A new approach of the situ hydrolysis of acetonitrile is reported, and the slow release of small ligand CH3COO- is realized in the design and synthesis of high-nuclearity lanthanide clusters. A large lanthanide-exclusive cluster complex, [Gd60(CO3)8(CH3COO)12(µ2-OH)24(µ3-OH)96(H2O)56](NO3)15Br12(dmp)5·30CH3OH·20Hdmp (1-Gd60), was isolated under solvothermal conditions. To the best our knowledge, cluster 1 possesses the high metal/ligand ratio (magnetic density) and the largest magnetic entropy change (- Δ Smmax = 48.0 J kg-1 K-1 at 2 K for Δ H = 7 T) among previously reported high-nuclearity lanthanide clusters.

Two Pairs of Chiral "Tower-Like" Ln4 Cr4 (Ln=Gd, Dy) Clusters: Syntheses, Structure, and Magnetocaloric Effect.

Two pairs of novel chiral chromium lanthanide compounds, formulated as l- and d-[Gd4 Cr4 (IN)10 (µ3 -OH)4 (µ4 -O)4 (H2 O)12 ]⋅[IN]2 ⋅8 H2 O (1 and 3), and l- and d-[Dy4 Cr4 (IN)11 (µ3 -OH)4 (µ4 -O)4 (H2 O)8 ]⋅[IN]⋅1.5 H2 O (2 and 4) (HIN=isonicotinic acid) have been successfully synthesized and characterized. Structural analysis reveals that four Ln3+ ions and four Cr3+ ions connect with each other and yield a "tower-like" [Ln4 Cr4 ] skeleton. Apart from the above featuring an aesthetically charming structure, circular dichroism (CD) spectra confirm that compounds 1 and 3, 2 and 4 are enantiomers. To the best of our knowledge, these are the largest chiral chromium lanthanide compounds. In addition, magnetic interaction shows that Gd (the mixture of 1 and 3) exhibits significant cryogenic magnetocaloric effect (MCE) with -ΔSm =18.08 J kg-1 K-1 (34.69 mJ cm-3 K-1 ). Also, the observed second-harmonic generation efficiencies of [Gd4 Cr4 (IN)10 (µ3 -OH)4 (µ4 -O)4 (H2 O)12 ]⋅[IN]2 ⋅8 H2 O and [Dy4 Cr4 (IN)11 (µ3 -OH)4 (µ4 -O)4 (H2 O)8 ]⋅[IN]⋅1.5 H2 O are 0.3 and 0.4 times that of urea, respectively.

Two Polyoxometalate-Based Hybrid Compounds Modified by Iron Schiff Base Complexes: Syntheses, Crystal structures, Cyclic Voltametric Studies and Nonlinear Optical Properties.

Two new polyoxometalate (POM)-based hybrid compounds modified by a Schiff base, [Fe(DAPSC)(H2 O)2 ]2 [HPMo2 V Mo10 VI O40 ] ⋅ 5H2 O (1) and [Fe(DAPSC)(H2 O)]2 [HPV3 IV Mo4 V Mo7 VI O42 ] ⋅ 6H2 O (2), (DAPSC=2,6-diacetylpyridine bis-(semicarbazone)), have been successfully constructed from typical Keggin POMs, iron ions, and DAPSC ligands under hydrothermal condition. Structural analysis demonstrates that the Fe-Schiff base ligand units are free from polyacid anions in compound 1. While in compound 2, the Fe-Schiff base ligand units are bridged with polyacid anions via Fe-O bonds to emerge a stable double-supported skeleton. Noticeably, owing to the introduction of vanadium in H5 PMo10 V2 O40 ⋅ 32.5H2 O, a divanadium-capped configuration is shaped in compound 2. Besides, the third-order nonlinear optical (NLO) properties of two compounds were explored. It should be noted that both compounds 1 and 2 have two-photon absorption properties, which indicates that the two compounds are potential nonlinear optical materials.

Application of temperature-controlled chiral hybrid structures constructed from copper(ii)-monosubstituted Keggin polyoxoanions and copper(ii)-organoamine complexes in enantioselective sensing of tartaric acid.

Temperature usually occupies a crucial position in the construction of chiral compounds. By controlling the temperature of the reaction system, chiral and non-chiral compounds can be designed and synthesized. Given the above, three new chiral and non-chiral compounds based on copper(ii) monosubstituted polyoxoanions and Cu(en) complexes (en = ethylenediamine), d/l-[Cu(H2O)(en)2]2{[Cu(H2O)2(en)][SiCuW11O39]}·5H2O (1, d-1 and l-1) and [Cu(H2O)(en)2]{[Cu(en)2]2[SiCuW11O39]}·2.5H2O (2), were successfully synthesized under hydrothermal conditions. The main synthesis conditions of compound 1 (d-1 and l-1) and compound 2 are the same, however, the only difference is that the reaction temperatures are 80 °C and 140 °C, respectively. What's more, compounds 1 and 2 can form a 1D chiral chain by Cu-O and W/Cu-O-W/Cu bonds, respectively, and further obtain a 3D-supramolecular framework through hydrogen bonding interaction. Meanwhile, due to the asymmetry of chiral compound 1, optical second-harmonic generation (SHG) was used to investigate the second-order nonlinear optical effect and it was found that the observed SHG efficiency of compound 1 is 0.3 times that of urea. To further investigate the chiral properties, d-1 and l-1 were used in the electrochemical enantioselective sensing of d-/l-tartaric acid (d-/l-tart) molecules, respectively, which demonstrates that d-1 and l-1 have a good application prospect in sensing chiral substances.

Two 3D Mn-based coordination polymers: synthesis, structure and magnetocaloric effect.

Two three-dimensional (3D) coordination polymers, namely MnII 6(CH3COO)2(HCOO)2(IN)8(C4H8O)2(H2O) and MnIII 6MnII 12(µ3-O)6(CH3COO)12(IN)18(H2O)7.5 (abbreviated as Mn II 6 and Mn II 12 Mn III 6 respectively; HIN = isonicotinic acid), were synthesized by the reaction of Mn(CH3COO)2·4H2O and isonicotinic acid under solvothermal conditions. Magnetic studies revealed that antiferromagnetic interactions may be present in compounds Mn II 6 and Mn II 12 Mn III 6 . Moreover, the values of -ΔS m (26.27 (Mn II 6 ) and 37.69 (Mn II 12 Mn III 6 ) J kg-1 K-1 at ΔH = 7 T) are relatively larger than those of the reported Mn-based coordination polymers. This work provides a great scope in the magnetocaloric effect (MCE) of pure 3d-type systems.

Two new isolated Zn-ε-Keggin clusters modified by conjugated organic ligands with decent electrocatalytic and third-order NLO properties.

Two new bifunctional isolated hybrid compounds, [ε-PMoV8MoVI4O37(OH)3Zn4][iql]4·6H2O (1) and [ε-PMoV8MoVI4O38(OH)2Zn4][bipy]3[(CH3COO)(bipy)2Zn]·2H2O (2) (where iql = isoquinoline and bipy = 2,2'-bipyridine), based on Zn-ε-Keggin were successfully synthesized by self-assembly under hydrothermal conditions. It is interesting to note that acetate in 2 acted as a linker connecting the ε-Keggin anion with the one Zn atom (Zn5) and enabled the ε-Keggin anion to coordinate with more bipy ligands, culminating with a larger isolated system, which is the first reported isolated cluster of Zn5PMo12. Meanwhile, compounds 1-2 show great electrochemical behaviors and excellent electrocatalytic activity for the degradation of NaNO2. In addition, compound 2 displays better third-order NLO performance than 1 due to the presence of more conjugated rings, with a TPA cross section (σ) of 1819 GM, which suggests that compound 2 has the potential to function as a bifunctional material with tremendous prospects.

Synthesis, crystal structures and magnetic properties of two heterometallic {Ln8Cr4} (Ln = Gd3+ and Tb3+) complexes with one-dimensional wave chain structure.

Two isomorphic heterometallic 3d-4f cluster-based materials, formulated [Gd8Cr4(IN)18(µ3-O)2(µ3-OH)6(µ4-O)4(H2O)10]·13H2O (1) and [Tb8Cr4(IN)18(µ3-O)2(µ3-OH)6(µ4-O)4(H2O)10]·13H2O (2) (abbreviation: {Ln8Cr4}: Ln = Gd3+ (1); Tb3+ (2); HIN = isonicotinic acid), were achieved by hydro-/solvothermal method through using the ligand HIN. X-ray diffraction analysis illustrates eight lanthanide ions (Ln = Gd3+, Tb3+) and four transition-metal ions (Cr3+) of {Ln8Cr4} were constructed from two classical "drum-like" {Ln4Cr2} structures associated by organic ligands HIN, displaying a one-dimensional wave chain structure, which is rare. The magnetic properties of {Gd8Cr4} were inspected and showed the existence of antiferromagnetic coupling interactions between contiguous metal ions. On top of this, the magnetic entropy change of ΔS m can attain 23.40 J kg-1 K-1 (44.90 mJ cm-3 K-1) at about 3 K and ΔH = 7 T. Besides, fluorescence measurements of {Tb8Cr4} display typical characteristic Tb-based luminescence.

Polyoxometalate-Based Metal-Organic Frameworks with Unique High-Nuclearity Water Clusters.

The maximum exposure of polyoxometalates (POMs) is of great significance to enhance the catalytic performance of HKUST-1 with incorporated Keggin-type POMs. Herein, two phosphovanadomolybdates were encapsulated into the HKUST-1 via a hydrothermal method to obtain two polyoxometalate-based metal-organic frameworks, formulated as [Cu12(BTC)8(H2O)12][H4PMo11VO40]@(H2O)30 (1) and [Cu12(BTC)8(H2O)12][H5PMo10V2O40]@(H2O)49 (2). Single-crystal X-ray diffraction analysis indicates that two compounds contain unique high-nuclearity water clusters without organic counter cations. The octahedral-shaped water cluster (H2O)30 was constructed from square-pyramid-shaped (H2O)5 for compound 1, while the huge cage-shaped water cluster (H2O)49 of compound 2 consisted of crown-like (H2O)8 and one water molecule, which substitute the organic counter cations involved in the structural construction. More importantly, after removing the water clusters via simple heat treatment, the active sites of the two compounds were fully exposed, leading to good catalytic activities for both benzene hydroxylation reaction and oxidative desulfurization. Furthermore, the catalytic test confirmed that compound 2 may be a bifunctional heterogeneous catalyst with great promise for both benzene hydroxylation and oxidative desulfurization.

3D Enantiomorphic Mg-Based Metal-Organic Frameworks as Chemical Sensor of Nitrobenzene and Efficient Catalyst for CO2 Cycloaddition.

Two enantiomorphic MgII -based metal-organic frameworks, {MgL(H2 O)2 }n (1-D and 1-L) (where H2 L=2,2'-bipyridyl-4,4'-dicarboxylic acid) have been synthesized by solvothermal reaction without any chiral auxiliary. The single-crystal X-ray measurement and the structural analysis indicate that both 1-D and 1-L possess 2-fold interpenetrated frameworks with different left- and right-handed helical chains simultaneously, which serve as chiral source, thus transmitting chirality over the whole frameworks. The fluorescence measurements reveal that they exhibit a strong quenching response to nitrobenzene and could be potentially used as a chemical sensor. Owing to the accessible Lewis acidic sites in channels, they display high catalytic efficiency for cycloaddition reaction of CO2 with epoxides and could be reused five times without losing activity.

A huge novel polyoxometalate-based cluster Fe10P4W32 exhibiting prominent electrocatalytic activity for the oxygen evolution reaction and third-order NLO properties.

Two novel POM-based huge clusters modified by conjugated organic ligands (DAPSC), {Fe10P4W32} and {Fe8MoW18}, have been successfully isolated. Compound 1 consists of a novel huge inorganic building block {Fe10P4W32} and four organic groups DAPSC linked by ten iron ions and four sodium ions. The DAPSC ligands enhance the electric delocalization effects of polyoxoanions, leading to strengthening of the third-order nonlinear optical (NLO) responses of compounds 1-2. Additionally, the oxygen evolution reaction (OER) electrocatalytic activity and the magnetic properties of compound 1 have also been investigated.

Three new high-nuclear transition-metal-substituted heteropolytungstates: syntheses, crystal structures, magnetic studies and NLO properties.

Three new nickel-cluster-substituted polyoxometalates (POMs), [Ni6(H2O)9(µ3-OH)3(HSiW9O34)]2·12H2O (1), [Ni(en)(H2O)3][Ni6(H2O)3(en)2L(µ3-OH)3(HSiW9O34)]2·9H2O (2) (en = ethylenediamine; L = C7H5O2 = benzoic acid) and [Ni6(L')6(CH3COO)(H2O)3(µ3-OH)3(HPW9O34)]2·9H2O (3) (L' = C5NH5 = pyridine) were successfully isolated under hydro-/solvothermal conditions. 1-3 were structurally characterized by single-crystal XRD, elemental analyses, PXRD, IR, and TGA. Compound 1 mainly consists of a pair of {Ni6SiW9} fragments and some water molecules. Interestingly, the whole structure can be regarded as the connection of {Ni6SiW9} and another unit rotated 180° through Ni-O-W bonds, forming a dimeric structure {Ni6SiW9}2. Compounds 2 and 3 also have an {Ni6XW9}2 (X = Si, P) dimer, but there is a big difference in the connection between {Ni6SiW9} units. On this basis, mono-dentate conjugated organic ligands (benzoic acid (L) and pyridine (L')) were successfully introduced. It is noteworthy that pyridine molecules were first integrated into {Ni6SiW9}-based clusters and 3 features the highest number of organic ligands (six pyridines per Ni6) in the reported {Ni6XW9}-based clusters. The introduction of organic ligands to compounds 2 and 3 can bring about better third-order nonlinear optical properties. Magnetic research indicated the existence of ferromagnetic interactions in 2-3.

Two new POM-based compounds modified by lanthanide-Schiff base complexes with interesting NLO properties.

Two POM-based lanthanide derivatives, namely {triaqua[2,6-diacetylpyridine bis(semicarbazone)-κ5O,N,N',N'',O']terbium(III)}-µ-oxido-[tricosa-µ2-oxido-dodecaoxido-µ12-phosphato-dodecamolybdenum(VI)] pentahydrate (1), [Tb(C11H15N7O2)(H2O)3][PMo12O40]·5H2O, and the dysprosium(III) analogue (2), have been isolated successfully by the reaction of Keggin-POM [PMo12O40]3- (abbreviated as PMo12), the Ln3+ ion and the Schiff base 2,6-diacetylpyridine bis(semicarbazone) (DAPSC) ligand under hydrothermal conditions. [Ln(DAPSC)(H2O)3][PMo12O40]·5H2O is a PMo12-supported cluster featuring a lanthanide-Schiff base complex [denoted Ln-L(Schiff base)]. Single-crystal X-ray diffraction analysis reveals that the LnIII ion is in a distorted tricapped trigonal prismatic arrangement, coordinated by six O atoms and three N atoms. Two O atoms and three N atoms are provided by one DAPSC ligand, while the additional O atoms originate from a PMo12 cluster and three water molecules. Hydrogen-bonding interactions between adjacent clusters form an interesting three-dimensional supramolecular structure. The identities of 1 and 2 were characterized by IR spectroscopy, thermogravimetric analysis and powder X-ray diffraction. Interestingly, both compounds possess excellent two-photon absorption (TPA) responses to the third-order nonlinear optics (NLO) (2264 GM for 1 and 941 GM for 2), suggesting that they have potential applications in the field of nonlinear optics (NLO). To our knowledge, 1 and 2 are the first POM-based Ln-L(Schiff base) complexes showing excellent two-photon responses. Meanwhile, the electrochemical properties of both compounds were studied in detail.

Proton conductivity resulting from different triazole-based ligands in two new bifunctional decavanadates.

Triazole, similarly to imidazole, makes a prominent contribution to the proton conductivity of porous materials. To investigate the effects of triazole-based ligands in polyoxovanadates (POVs) on proton conduction, we designed and synthesized two decavanadate-based POVs, [Zn3(C2H4N4)6(H2O)6](V10O28)·14H2O (1) and [Zn3(C2H3N3)8(H2O)4](V10O28)·8H2O (2) constructed from the ligands 3-amino-1,2,4-triazole and 1H-1,2,4-triazole, respectively, via an aqueous solution evaporation method. Surprisingly, complex 1 obtained a superior proton conductivity of 1.24 × 10-2 S cm-1 under 60 °C and 98% RH, which is much higher than that of complex 2. Furthermore, due to the contribution of the conjugate properties of the ligands to the third-order nonlinear optical (NLO) properties, we also studied its two-photon responses and achieved satisfactory results.