Polymorphism and Its Influence on Catalytic Activities of Lanthanide-Glutamate-Oxalate Coordination Polymers.

To study the relationship between polymorphism and catalytic activities of lanthanide coordination polymers in the cycloaddition reactions of CO2 with epoxides, the monoclinic and triclinic polymorphs of [LnIII(NH3-Glu)(ox)]·2H2O, where LnIII = LaIII (I), PrIII (II), NdIII (III), SmIII (IV), EuIII (V), GdIII (VI), TbIII (VII), and DyIII (VIII), NH3-Glu- = NH3+ containing glutamate, and ox2- = oxalate, were synthesized and characterized. Factors determining polymorphic preference, the discrepancy between the two polymorphic framework structures, potential acidic and basic sites, thermal and chemical stabilities, active surface areas, void volumes, CO2 sorption/desorption isotherms, and temperature-programmed desorption of NH3 and CO2 are comparatively presented. Based on the cycloaddition of CO2 with epichlorohydrin in the presence of tetrabutylammonium bromide under solvent-free conditions and ambient pressure, catalytic activities of the two polymorphs were evaluated, and the relationship between polymorphism and catalytic performances has been established. Better performances of the monoclinic catalysts have been revealed and rationalized. In addition, the scope of monosubstituted epoxides was experimented and the outstanding performance of the monoclinic catalyst in the cycloaddition reaction of CO2 with allyl glycidyl ether under ambient pressure has been disclosed.

Postsynthetic Installation of Lanthanide Cubane Clusters in a 3D Hydrogen-Bonded Framework of IrIII4ZnII4 Multicarboxylates.

Immersing single crystals of (Δ)4-K6[Ir4Zn4O(l-cysteinate)12]·nH2O (K6[1Ir]·nH2O) bearing 12 free carboxylate groups, which was newly prepared from Δ-H3[Ir(l-cysteinate)3], ZnBr2, ZnO, and KOH, in an aqueous solution of lanthanide(III) acetate produced Ln2[1Ir]·nH2O (2Ln; Ln = LaIII, CeIII, PrIII, and NdIII) and Ln0.33[Ln4(OH)4(OAc)3(H2O)7][1Ir]·nH2O (3Ln; Ln = SmIII, EuIII, GdIII, TbIII, DyIII, ErIII, HoIII, TmIII, YbIII, and LuIII) in a single-crystal-to-single-crystal transformation manner. X-ray crystallography showed that the KI ions in K6[1Ir]·nH2O are completely exchanged by the LnIII ions in 2Ln and 3Ln, retaining the 3D hydrogen-bonded framework that consists of the IrIII4ZnII4 complex anions of [1Ir]6-. While 2Ln contained the LnIII ions as isolated aqua species, the LnIII ions in 3Ln existed as cationic cubane clusters of [Ln4(OH)4(OAc)3(H2O)7]5+; these were linked by [1Ir]6- anions through carboxylate groups in a 3D polymeric structure. 3Ln showed magnetic and photoluminescence properties that are characteristically observed for discrete LnIII species in the solid state.

Silver(I) Sulfide Clusters Protected by Rhodium(III) Metalloligands with 3-Aminopropanethiolate.

The two homochiral AgIRhIII nanoclusters, Δ6/Λ6-[Ag11S{Rh(apt)3}6]9+ ([1]9+) and Δ6/Λ6-[Ag13S{Rh(apt)3}6]11+ ([2]11+), in which Ag11S and Ag13S cluster cores, respectively, are protected by fac-[Rh(apt)3] metalloligands, were newly synthesized from fac-[Rh(apt)3] (Hapt = 3-aminopropanethiol) and Ag+ in water in combination with sulfide sources. While [1]9+ was produced by using d-penicillamine as a sulfide source, the use of HS- as a sulfide source afforded [2]11+ without causing any precipitation of Ag2S. Cluster [1]9+ was convertible to [2]11+ via the reaction with Ag+, which led to a turn-on-type switch in photoluminescence from nonemissive [1]9+ to emissive [2]11+.

Jahn-Teller Switching of a Redox-Active Nickel(III) Center in a Homoleptic Thiolato Metalloligand Environment.

Treatment of nickel(II) nitrate with the iridium(III) metalloligand fac-[Ir(apt)3] (apt = 3-aminopropanethiolate) gave the trinuclear complex [Ni{Ir(apt)3}2](NO3)3 ([1Ir](NO3)3), in which the nickel center has a formal oxidation state of +III. Chemical or electrochemical oxidation and reduction of [1Ir](NO3)3 generated the corresponding trinuclear complexes [Ni{Ir(apt)3}2](NO3)4 ([1Ir](NO3)4) and [Ni{Ir(apt)3}2](NO3)2 ([1Ir](NO3)2) with one-electron oxidated and reduced states, respectively. Single-crystal X-ray crystallography revealed that the nickel center in [1Ir](NO3)3 is situated in a highly distorted octahedron due to Jahn-Teller effect, while the nickel center in each of [1Ir](NO3)4 and [1Ir](NO3)2 adopts a normal octahedral geometry. Crystals of [1Ir](NO3)3·2H2O are dehydrated on heating while retaining their single-crystallinity. The dehydration induces temperature-dependent dynamic disorder of the Jahn-Teller distortion at the nickel(III) center, which is largely quenched upon rehydration of the crystal.

Racemic Tartrate/Malate Anions Combine with Racemic Complex Cations to Form Optically Active Ionic Crystals.

Spontaneous resolution has attracted continuing attention in various research fields since Pasteur's work on the crystallization behavior of racemic tartrate. Here, a unique example of this phenomenon is reported, involving ionic crystals generated from racemic RR/SS- tartrate or R/S-malate and racemic ΔΔ/ΛΛ-[Ag3 Rh2 (2-aminoethanethiolato)6 ]3+ (ΔΔ/ΛΛ-[1]3+ ) in water. RR- and SS-tartrate selectively recognize the ΛΛ and ΔΔ isomers of [1]3+ to produce ionic crystals of (ΛΛ-[1])2 (RR-tartrate)3 and (ΔΔ-[1])2 (SS-tartrate)3 , respectively, which can undergo spontaneous resolution. While spontaneous resolution also occurs when using R/S-malate, R- and S-malate select the opposite isomers of [1]3+ to give ionic crystals of (ΔΔ-[1])2 (R-malate)3 and (ΛΛ-[1])2 (S-malate)3 , respectively. In the presence of S-aspartate, (ΛΛ-[1])2 (R-tartrate)3 and (ΔΔ-[1])2 (S-tartrate)3 are preferentially crystallized from ΔΔ/ΛΛ-[1]3+ and RR/SS-tartrate at solution pH values of 6 and 10, respectively. This finding provides significant insight into the optical resolution of chemical species by spontaneous resolution and the origin of homochirality in nature.

Insertion of a Hydride Ion Into a Tetrasilver(I) Cluster Covered by S-Donating Rhodium(III) Metalloligands.

Here, we report a tetrahedral silver(I) cluster of {Ag4}4+ covered by Δ-[Rh(l-cys)3]3- (l-H2cys = l-cysteine), which is converted to an {Ag4H}3+ cluster via the inclusion of a H- ion. The 1:1 reaction of Δ-[Rh(l-cys)3]3- with Ag+ gave a sulfur-bridged AgI4RhIII4 octanuclear structure in [Ag4{Rh(l-cys)3}4]8- ([1]8-), in which a tetrahedral {Ag4}4+ core is bound by four Δ-[Rh(l-cys)3]3- units through thiolato groups. DFT calculations revealed that a superatomic orbital exists in {Ag4}4+ as the lowest unoccupied molecular orbital, contributing to the appearance of a characteristic charge-transfer transition in the visible region for [1]8-. Treatment of [1]8- with NaBH4 led to the insertion of a H- ion to generate [Ag4H{Rh(l-cys)3}4]9- ([2]9-) with an {Ag4H}3+ core, accompanied by the disappearance of the visible band for [1]8-. The presence of a H- ion in the center of [2]9- was established by the 1H NMR spectrum, which reveals a unique quintuple-quintet signal from the H- ion surrounded by four AgI atoms. [2]9- was considerably stable in aqueous media, which is ascribed to a chemical bond between the unoccupied superatomic orbital of {Ag4}4+ and the occupied orbital of H- in the {Ag4H}3+ core.

Highly Porous Ionic Solids Consisting of AuI3CoIII2 Complex Anions and Aqua Metal Cations.

Treatment of Na3[Au3Co2(d-pen)6] (Na3[1]; d-H2pen = d-penicillamine) with M(OAc)2 (M = NiII, MnII) in water gave ionic crystals of [M(H2O)6]3[1]2 (2M) in which [1]3- anions are hydrogen-bonded with [M(H2O)6]2+ cations to form a 3D porous framework with a porosity of ca. 80%. Soaking crystals of 2Ni in its mother liquor afforded crystals of [Ni(H2O)6]2[{Ni(H2O)4}(1)2] (3Ni) in which [1]3- anions are connected to trans-[Ni(H2O)4]2+ and [Ni(H2O)6]2+ cations through coordination and hydrogen bonds, respectively, to form a 1D porous framework with a porosity ca. 60%. Further soaking crystals led to [{Ni(H2O)4}3(1)2] (4Ni), in which [1]3- anions are connected to cis-[Ni(H2O)4]2+ and trans-[Ni(H2O)4]2+ cations through coordination bonds in a dense framework with a porosity of ca. 30%. A similar two-step crystal-to-crystal transformation mediated by solvent proceeded when crystals of 2Mn were soaked in a mother liquor. However, the transformation of 2Mn generated [{Mn(H2O)4}(H1)] (4'Mn) as the final product, in which [H1]2- anions are connected to cis-[Mn(H2O)4]2+ cations through coordination bonds in a very dense framework with a porosity ca. 5% by way of [Mn(H2O)6]2[{Mn(H2O)4}(1)2] (3Mn), which is isostructural with 3Ni. While all the compounds adsorbed H2O and CO2 depending on the degree of their porosity, unusually large NH3 adsorption capacities were observed for 4Ni and 4'Mn, which have dense frameworks.

A 116-Nuclear Metallosupramolecular Cage-of-Cage Showing Multistep Single-Crystal-to-Single-Crystal Transformation.

Here a unique single-crystal-to-single-crystal (SCSC) transformation of a 116-nuclear AuI 72 CdII 40 NaI 4 cage-of-cage (2CdNa ) is reported, which was created from a trigold(I) metalloligand with d-penicillamine by way of a 9-nuclear AuI 6 CdII 3 cage (1). Cage-of-cage 2CdNa is composed of 12 cages of 1 that are linked by 4 Cd2+ and 4 Na+ ions, with its surface being covered by 12 NO3 - ions to form a discrete, spherical molecule with a diameter ca. 4.7 nm. In crystal 2CdNa , the cage-of-cage molecules are packed in a cubic lattice with a huge cell volume of ca. 4.5×105  Å3 , so as to have large interstices with diameters of more than 3 nm. Upon soaking crystals 2CdNa in aqueous Cu(NO3 )2 , all Cd2+ and Na+ were quickly exchanged by Cu2+ to produce an analogous AuI 72 CuII 44 cage-of-cage (2Cu ) in a SCSC manner. Prolonged soaking led to the SCSC transformation to another supramolecular structure (2'Cu ) consisting of 152-nuclear AuI 72 CuII 80 cage-of-cages that are alternately H-bonded with the AuI 72 CuII 44 cage-of-cages. 2'Cu showed the accommodation of MoO4 2- and the conversion of MoO4 2- to ß-Mo8 O26 4- in the crystal, with retention of single-crystallinity.

Elucidating the Structural Chemistry of a Hysteretic Iron(II) Spin-Crossover Compound From its Copper(II) and Zinc(II) Congeners.

Annealing [FeL2 ][BF4 ]2 ⋅2 H2 O (L=2,6-bis-[5-methyl-1H-pyrazol-3-yl]pyridine) affords an anhydrous material, which undergoes a spin transition at T1/2 =205 K with a 65 K thermal hysteresis loop. This occurs through a sequence of phase changes, which were monitored by powder diffraction in an earlier study. [CuL2 ][BF4 ]2 ⋅2 H2 O and [ZnL2 ][BF4 ]2 ⋅2 H2 O are not perfectly isostructural but, unlike the iron compound, they undergo single-crystal-to-single-crystal dehydration upon annealing. All the annealed compounds initially adopt the same tetragonal phase but undergo a phase change near room temperature upon re-cooling. The low-temperature phase of [CuL2 ][BF4 ]2 involves ordering of its Jahn-Teller distortion, to a monoclinic lattice with three unique cation sites. The zinc compound adopts a different, triclinic low-temperature phase with significant twisting of its coordination sphere, which unexpectedly becomes more pronounced as the crystal is cooled. Synchrotron powder diffraction data confirm that the structural changes in the anhydrous zinc complex are reproduced in the high-spin iron compound, before the onset of spin-crossover. This will contribute to the wide hysteresis in the spin transition of the iron complex. EPR spectra of copper-doped [Fe0.97 Cu0.03 L2 ][BF4 ]2 imply its low-spin phase contains two distinct cation environments in a 2:1 ratio.

A Dynamic Combinatorial Library of Cyclic AuI2NiII Complexes with Cysteine/Penicillamine Showing Solvent-Controlled Crystallization.

A dynamic combinatorial library (DCL) is a set of molecular species existing in equilibrium in solution that can undergo self-assembly via reversible chemical bonds. Here, we report a unique DCL system that shows the independent crystallization of products from solvents with slightly different polarities. The reaction of a 1:1 mixture of [Au2(dppm)(dl-cys)2]2- and [Au2(dppm)(dl-pen)2]2- with Ni2+ in solution gave a DCL containing 10 cyclic AuI2NiII molecules of [Au2Ni(dppm)(dl-cys/dl-pen)2]. Upon crystallization, three kinds of enantiomeric pairs, homoleptic-heterochiral C/A-[Au2Ni(dppm)(d-cys)(l-cys)], homoleptic-homochiral [Au2Ni(dppm)(d-pen)2]/[Au2Ni(dppm)(l-pen)2], and heteroleptic-homochiral [Au2Ni(dppm)(d-cys)(d-pen)]/[Au2Ni(dppm)(l-cys)(l-pen)], were produced from the reaction solutions of MeOH, MeOH/H2O, and EtOH/H2O, respectively. The independent crystallization was explained by a combination of the different hydrogen-bonding interactions of the AuI2NiII molecules in the crystal and the different thermodynamic stabilities of the molecules in solution.

Charge-Separation-Type Ionic Crystals with Mixed AuI4CoIII2 and AuI4NiIICoIII Hexanuclear Complexes.

Treatment of a digold(I) metalloligand, [AuI2(dppe)(d-Hpen)2] (H2LAu; d-H2pen = d-penicillamine, dppe = 1,2-bis(diphenylphosphino)ethane), with a 1:1 mixture of Co(OAc)2 and Ni(OAc)2 under aerobic conditions resulted in the formation of three types of hexanuclear complexes: [CoIII2(LAu)2]2+, [NiIICoIII(LAu)2]+, and [NiII2(LAu)2]. The addition of NaNO3, M1NO3 (M1 = K, Rb, Cs), and M2(NO3)2 (M2 = Ca, Sr, Ba) to the reaction mixture led to co-crystallization of [CoIII2(LAu)2]2+ and [NiIICoIII(LAu)2]+ as a solid solution to form the charge-separation (CS)-type ionic crystals 1Na, 1M1, and 1M2, respectively, while [NiII2(LAu)2] independently crystallized as a single species (2). In 1Na, [CoIII2(LAu)2]2+ and [NiIICoIII(LAu)2]+ cations assemble in a 1:2 ratio to form a cationic supramolecular octahedron accommodating 4 H3O+ ions, while 10 nitrate ions are packed in each hydrophilic tetrahedral interstice of the crystal to form an anionic adamantane cluster. The overall structures of 1M1 and 1M2 are very similar to that of 1Na, having a CS-type structure composed of cationic supramolecular octahedra with a +12 charge and anionic inorganic clusters with a -10 charge. However, 1M1 contains M1 ions in place of the H3O+ ions in 1Na, and furthermore, a novel rhombic dodecahedron cluster composed of 14 nitrate ions, which encapsulates two M2 ions, is formed in each hydrophilic tetrahedral interstice in 1M2.

Heterochiral-to-Homochiral Structural Transformation in Metallosupramolecular Ionic Crystals.

Here, we report a unique transformation from heterochiral to homochiral structures in ionic crystals composed of complex cations and complex anions. Treatment of an anionic AuI3CoIII2 complex, ΛΛ-[Au3Co2(d-pen)6]3- ([1]3-; H2pen = penicillamine), with M = MnII, CoII, NiII, ZnII in water in the presence of 1,10-phenanthroline (phen) commonly gave ionic crystals formulated as [M(phen)2(H2O)2][Na(H2O)6][{M(phen)2(H2O)}(1)]3 (2M), in which [M(phen)2(H2O)2]2+ and [M(phen)2(H2O)]2+ adopt Δ and Λ configurations, respectively. While 2Co, 2Ni, and 2Zn were all stable in each mother liquor, 2Mn was converted to [Mn(phen)3]3[1]2·phen (3Mn) containing the Λ configurational [Mn(phen)3]3+ under the same conditions. 3Mn showed a water adsorption capacity higher than that of 2Mn, despite its lower porosity of crystal.

Gas Adsorption, Proton Conductivity, and Sensing Potential of a Nanoporous Gadolinium Coordination Framework.

The new nanoporous framework [Gd4(di-nitro-BPDC)4(NO2)3(OH)(H2O)5]·(solvent) (I; di-nitro-BPDC2- = 2,2'-dinitrobiphenyl-4,4'-dicarboxylate) has been designed and synthesized through a simple one-pot reaction. In addition to its exceptional thermal and water stabilities, I exhibited multifunctional properties. A sudden CO2 uptake to a maximum of 4.51 mmol g-1 (195 K and 1 bar) with notable selectivity over O2 and N2 (CO2/O2 = 39 at 195 K and 0.10 bar, CO2/N2 = 46 at 195 K and 0.10 bar) and an isosteric adsorption enthalpy of 20.7(4) kJ mol-1 have been revealed. Depending on the temperature and humidity, I also showed distinguished superprotonic conductivities with a maximum value and activation energy of 6.17 × 10-2 S cm-1 (55 °C, 99 RH%, and 1 V AC voltage) and 0.43 eV, respectively. With respect to the linear dependence of conductivities on both temperature (25-55 °C at 99 RH%) and humidity (55-99 RH% at 25 °C), the potential of I in temperature and humidity sensing was evaluated, disclosing an excellent sensing resolution and exceptional accuracy, precision, and repeatability for the measurements.

Modulating the Magnetic Properties of Copper(II)/Nitroxyl Heterospin Complexes by Suppression of the Jahn-Teller Distortion.

A series of six-coordinate [Cu(L)L1][BF4]2 (L1 = 2,6-bis{1-oxyl-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-2-yl}pyridine) complexes are reported. Ferromagnetic coupling between the Cu and L1 ligand spins is enhanced by an L coligand with distal methyl substituents, which is attributed to a sterically induced suppression of its Jahn-Teller distortion.

Single-Crystal-to-Single-Crystal Installation of Ln4 (OH)4 Cubanes in an Anionic Metallosupramolecular Framework.

Postsynthetic installation of lanthanide cubanes into a metallosupramolecular framework via a single-crystal-to-single-crystal (SCSC) transformation is presented. Soaking single crystals of K6 [Rh4 Zn4 O(l-cys)12 ] (K6 [1]; l-H2 cys=l-cysteine) in a water/ethanol solution containing Ln(OAc)3 (Ln3+ =lanthanide ion) results in the exchange of K+ by Ln3+ with retention of the single crystallinity, producing Ln2 [1] (2Ln ) and Ln0.33 [Ln4 (OH)4 (OAc)3 (H2 O)7 ][1] (3Ln ) for early and late lanthanides, respectively. While the Ln3+ ions in 2Ln exist as disordered aqua species, those in 3Ln form ordered hydroxide-bridged cubane clusters that connect [1]6- anions in a 3D metal-organic framework through coordination bonds with carboxylate groups. This study shows the utility of an anionic metallosupramolecular framework with carboxylate groups for the creation of a series of metal cubanes that have great potential for various applications, such as magnetic materials and heterogeneous catalysts.

Structurally Precise Silver Sulfide Nanoclusters Protected by Rhodium(III) Octahedra with Aminothiolates.

A 60-nuclear silver sulfide nanocluster with a highly positive charge (1) has been synthesized by mixing an octahedral RhIII complex with 2-aminoethanethiolate ligands, silver(I) nitrate, and d-penicillamine in water under mild conditions. The spherical surface of 1 is protected by the chiral octahedral RhIII complex, with cleavage of the C-S bond of the d-penicillamine supplying the sulfide ions. Although 1 does not contain d-penicillamine, it is optically active because of the enantiomeric excess of the RhIII molecules induced by chiral transfer from d-penicillamine. 1 can accommodate/release external Ag+ ions and replace inner Ag+ ions by Cu+ ions. The study demonstrates that a thiolato metal complex and sulfur-containing amino acid can be used as cluster-surface-protecting and sulfide-supplying regents, respectively, for creating chiral, water-soluble, structurally precise silver sulfide nanoclusters, the properties of which are tunable through the addition/removal/exchange of Ag+ ions.

2,6-Bis(pyrazol-1-yl)pyridine-4-carboxylate Esters with Alkyl Chain Substituents and Their Iron(II) Complexes.

Two series of 4-(alkoxyphenyl) 2,6-bis{pyrazol-1-yl}pyridine-4-carboxyate (L3R) or alkyl 2,6-bis{pyrazol-1-yl}pyridine-4-carboxyate (L4R) esters have been synthesized and complexed to iron(II), where R = C nH2 n+1 ( n = 6, 12, 14, 16, 18); two other derivatives related to L3R are also reported. While the solid [Fe(L4R)2][BF4]2 compounds are isostructural by powder diffraction and show similar spin state behaviors, the [Fe(L3R)2][BF4]2 series shows more varied structures and magnetic properties. This was confirmed by solvated crystal structures of [Fe(L3R)2][BF4]2 with n = 6, 14, 16, which all adopt the P1̅ space group but show significantly different side-chain conformations and/or crystal packing. The solid complexes are mostly low spin at room temperature, with many exhibiting the onset of thermal spin crossover (SCO) upon warming. Heating the complexes with n ≥ 14 significantly above their SCO temperature transforms them irreversibly into a predominantly high spin state, which is accompanied by structure changes and loss of crystallinity by powder diffraction. These transformations do not coincide with lattice solvent loss and may reflect melting and refreezing of their alkyl chain conformations during the thermal cycle. Four of the complexes exhibit SCO in CD3CN solution with T1/2 = 273-277 K, which is apparently unaffected by their alkyl chain substituents.

Valence Interconversion of Octahedral Nickel(II/III/IV) Centers.

Three oxidation states (+2, +3, +4) of an octahedral nickel center were stabilized in a newly prepared RhNiRh trinuclear complex, [Ni{Rh(apt)3 }2 ]n+ (apt=3- aminopropanethiolate), in which the nickel center was bound by six thiolato donors sourced from two redox-inert fac-[RhIII (apt)3 ] octahedral units. The three oxidation states of the octahedral nickel center were fully characterized by single-crystal X-ray crystallography, as well as spectroscopic, electrochemical, and magnetic measurements; all three were interconvertible, and the conversion was accompanied by changes in color, magnetism, and Jahn-Teller distortion.

Metallosupramolecular Structures Derived from a Series of Diphosphine-bridged Digold(I) Metalloligands with Terminal d-Penicillamine.

In this report, we describe our recent work on the development of a new family of chiral heteroleptic digold(I) metalloligands with mixed diphosphine and d-penicillaminate (d-pen), [Au2 (dppx)(d-pen-S)2 ](2-) (dppx = PPh2 (CH2 )n PPh2 , n = 1-5) and their application for the construction of chiral multinuclear and metallosupramolecular structures. The reactions of the metalloligands with 3d metal ions produce a variety of chiral heterobimetallic structures retaining the digold(I) metalloligand structure, ranging from discrete trinuclear to infinite helix structures that depend on the type of dppx. In addition, monophosphine and triphosphine analogues of the metalloligands were designed, and their coordination behavior is discussed to show the essential properties and potential extensibility of this class of metalloligands.

Methanol-Triggered Turn-On-Type Photoluminescence in L-Cysteinato Palladium(II) and Platinum(II) Complexes Supported by a Bis(diphenylphosphine) Ligand.

The selective detection of methanol by photoluminescence under environmental conditions has been a great challenge for materials science. Herein, a reversible, turn-on-type photoluminescence triggered by methanol vapor in square-planar palladium(II) and platinum(II) complexes, newly prepared from [MCl2(1,3-bis(diphenylphosphino)propane)] and L-cysteine, is reported. Both the "turn-on" and "turn-off" states of the complexes were crystallographically characterized, which revealed the presence of intermolecular OH···O and CH···π interactions between methanol and the complex molecules in the turn-on state. These interactions prevent the vibrational quenching of the luminescence, leading to the turn-on-type luminescence in this system.