Syntheses, crystal structures and MMCT properties of diruthenium-based cyanido-bridged RuV/VI2-NC-Ru complexes.

The goal of this study was to investigate how the electron-donating capability around the lower valent metal ion and the electron-accepting capability of the higher valent metal ion influence metal to metal charge transfer (MMCT) properties in mixed-valence complexes. A series of trinuclear ruthenium complexes represented as [Ru(ap-4-Me)(CHCOO)NCRuCpMe(dppe)][PF] (CpMe = polymethylcyclopentadienyl, = 0, 1, and 5; and dppe = 1, 2-bis(diphenylphosphino)ethane, ap-4-Me = 2-anilino-4-methylpyridine) and their one-electron oxidized products were synthesized and fully characterized. The UV-vis-NIR spectra confirmed that as the electron donor character of the CpMe(dppe)RuCN fragment enhanced or the electron-accepting capability of the higher valent diruthenium cluster increased, the Ru → RuV2 or RuVI2 Ru MMCT bands shifted to lower energies, which was supported by TDDFT calculations.

Electronic Transition and Magnetic Coupling Regulation in Trimetallic Complexes Featuring a New Bridging Ligand Obtained by Oxidative Addition.

A series of trimetallic complexes [Fe(μ-L)(py)]M() ( = 2, M = Mn, ; Fe, ; Co, ; Zn, ; = 3, M = Cd, ) with a new bridging ligand L (deprotonated 1,2--bis(2-mercaptoanil) oxalimidic acid) were synthesized and fully characterized by elemental analysis, single-crystal X-ray crystallography, IR, and Mössbauer spectra. Interestingly, the bridging ligand was obtained by oxidative addition of the (gma) ligand from the mononuclear precursor Fe()py (gma = glyoxal-bis(2-mercaptoanil)). In the obtained complexes, the bridging ligand L coordinates to the terminal Fe ions (intermediate-spin with S = 3/2) by the N, S atoms, and coordinate to the central metal M ion by the four O atoms.

Investigation of the electron transfer properties between metal centers in binuclear and trinuclear cyanido-bridged mixed valence complexes with /-configuration.

To investigate the electron transfer properties between metal centers and their influencing factors in binuclear and trinuclear cyanido-bridged mixed valence complexes with /-configuration, binuclear -[Cp(dppe)Fe(μ-NC)Ru(5,5'-dmbpy)(μ-CN)][PF] (cis-1[PF6]n, = 1, 2) and trinuclear /-[Cp(dppe)Fe(μ-NC)Ru(5,5'-dmbpy)(μ-CN)Fe(dppe)Cp][PF] (cis/trans-2[PF6]n, = 2, 3, 4) (Cp = 1,3-cyclopentadiene, dppe = 1,2-bis(diphenylphosphino)ethane, 5,5'-dmbpy = 5,5'-dimethyl-2,2'-bipyridyl) cyanido-bridged complexes were synthesized and well characterized. The experimental results indicate that the presence of the other terminal fragment Cp(dppe)Fe in cis-2[PF6]4 results in higher MMCT energy than that of cis-1[PF6]2. In addition, the -configuration is more conducive to electron transfer between metal centers than the -configuration in trinuclear cyanido-bridged mixed valence complexes.

Multiple MMCT properties of the diruthenium-based cyanido-bridged complex RuVI2-NC-Ru-CN-RuVI2.

The diruthenium-based linear mixed valence complex -[Ru(ap)-NC-Ru(DMAP)-CN-Ru(ap)][PF] (12+[PF6]2) (ap = 2-anilinopyridinate, DMAP = 4-dimethylaminopyridine) and its two-electron oxidation product 14+[PF6]4 have been synthesized and fully characterized. The investigation reveals that complex 12+ displays a single MMCT transition, whereas complex 14+ has three identified MMCT transitions (MMCT-1, MMCT-2 and MMCT-3) upon oxidation. Interestingly, MMCT-2 in complex 14+ might result from the transition from the Ru-NC-Ru-CN-Ru component, which is composed of the central Ru and its two neighboring Ru atoms from the cluster RuVI2 units, to both the terminal Ru atoms of the same cluster RuVI2 units, which is supported by the TDDFT calculations.

Effects of cis/trans-Configuration and Ligand Substitution of the Cyanidometal Bridge on Metal to Metal Charge Transfer Properties in Mixed Valence Complexes.

To investigate the effects of cis/trans-configuration of the cyanidometal bridge and the electron donating ability of the auxiliary ligand on the cyanidometal bridge on metal to metal charge transfer (MMCT) in cyanidometal-bridged mixed valence compounds, two groups of trinuclear cyanidometal-bridged compounds cis/trans-[Cp(dppe)Fe(μ-NC)Ru(4,4'-dmbpy) (μ-CN)Fe(dppe)Cp][PF ] (n=2 (cis/trans-1[PF ] ), 3 (cis/trans-1[PF ] ), 4 (cis/trans-1[PF ] )) and cis/trans-[Cp(dppe)Fe(μ-NC)Ru(bpy) (μ-CN)Fe(dppe)Cp][PF ] (cis/trans-2[PF ] ) were synthesized and fully characterized. The experimental results indicate that for these one- and two-electron oxidation mixed valence compounds, the trans-configuration compounds are more beneficial for MMCT than the cis-configuration compounds, and increasing the electron donating ability of the auxiliary ligand on the cyanidometal bridge is also conductive to MMCT. Moreover, compounds cis/trans-1[PF ] (n=3, 4) and cis/trans-2[PF ] belong to localized compounds by analyzing the experimental characterization results, supported by the TDDFT calculations.

Influence of Fine Ligand Substitution Modification of the Isocyanidometal Bridge on Metal-to-Metal Charge Transfer Properties in Class II-III Mixed Valence Complexes.

The synthesis and characterization of Class II-III mixed valence complexes have been an interesting topic due to their special intermediate behaviour between localized and delocalized mixed valence complexes. To investigate the influence of the isocyanidometal bridge on metal-to-metal charge transfer (MMCT) properties, a family of new isocyanidometal-bridged complexes and their one-electron oxidation products cis-[Cp(dppe)Fe-CN-Ru(L) -NC-Fe(dppe)Cp][PF ] (n=2, 3) (Cp=1,3-cyclopentadiene, dppe=1,2-bis(diphenylphosphino)ethane, L=2,2'-bipyridine (bpy, 1[PF ] ), 5,5'-dimethyl-2,2'-bipyridyl (5,5'-dmbpy, 2[PF ] ) and 4,4'-dimethyl-2,2'-bipyridyl (4,4'-dmbpy, 3[PF ] )) have been synthesized and fully characterized. The experimental results suggest that all the one-electron oxidation products may belong to Class II-III mixed valence complexes, supported by TDDFT calculations.

Tuning metal to metal charge transfer properties in cyanidometal-bridged complexes by changing the auxiliary ligand on the bridge.

In order to investigate the influence of the auxiliary ligand of the cyanidometal bridge on metal to metal charge transfer (MMCT) in cyanidometal-bridged complexes, two groups of heterotrimetallic cyanidometal-bridged complexes, trans-[Cp*(dppe)Fe-NC-Ru(L)2-CN-Fe(dppe)Cp*][PF6]n (L = bpy, 1(PF6)n; L = 4,4'-dmbpy, 2(PF6)n; n = 2, 3, 4) (Cp* = 1,2,3,4,5-pentamethylcyclopentadiene, dppe = 1,2-bis(diphenylphosphino)ethane, bpy = 2,2'-bipyridine, 4,4'-dmbpy = 4,4'-dimethyl-2,2'-bipyridyl) were synthesized and fully characterized. The MMCT of the one-electron oxidation mixed valence complexes is mainly attributed to RuII and FeII → FeIII MMCT transitions, and the MMCT of the two-electron oxidation complexes is mainly attributed to RuII → FeIII MMCT transitions. The energy of the MMCT of the four complexes decreases with the increase of the electron donating ability of the auxiliary ligand of the cyanidometal bridge.

The Electron Transfer Process in Mixed Valence Compounds with a Low-lying Energy Bridge in Different Oxidation States.

Mixed-valence compounds with the iso-cyanidometal-ligand bridge in different oxidation states are used as models for the investigation of the electron-transfer process. We synthesized a series of trimetallic isocyanidometal-bridged compounds with [Fe-CN-Ru-NC-Fe] (n=2-4), in which the one-electron oxidation product (N ) and two-electron oxidation product (N ) compounds possess an isocyanidometal bridge whose energy is, respectively lower and slightly higher than the terminal metal centers energies. For the N compounds, the bridge state (Fe -Ru -Fe ) and mixed-valence states (Fe -Ru -Fe or Fe -Ru -Fe ) could be simultaneously observed on the IR timescale.

Coordination tailoring of water-labile 3D MOFs to fabricate ultrathin 2D MOF nanosheets.

A novel coordination tailoring top-down delamination strategy involving the controllable partial disassembly of water-labile 3D MOFs has been explored to fabricate ultrathin 2D MOF nanosheets, and it exhibits many advantages such as green, convenience and high efficiency. Accordingly, 2D ultrathin MOF nanosheets with a two-fold interpenetrated architecture have been rapidly obtained from a 3D pillar-layered MOF, and they show distinguished fluorescence responses to different solvents.

Effects of ligand substituents on the single-molecule magnetic behavior of quinonoid-bridged dicobalt compounds.

A series of quinonoid-bridged dicobalt compounds [(NCo)LX](ClO) (1-4) (X = H, Cl, Br and OMe; N = 1,4,7,10-tetrabenzyl-1,4,7,10-tetraazacyclododecane) are synthesized and well characterized. Single crystal X-ray diffraction analyses reveal that the coordination geometry of one side Co in compounds 1-4 changes from a triangular prism to distorted octahedron with a change in the bridged-ligand substituent. Magnetic measurements show that compounds 1 and 3 exhibit single-molecule magnetic behavior.

A Diruthenium-Based Mixed Spin Complex Ru (S=1/2)-CN-Ru (S=3/2).

An unusual tetra-nuclear linear cyanido-bridged complex [Ru (μ-ap) -CN-Ru (μ-ap) ](BPh ) (1) (ap=2-anilinopyridinate) has been synthesized and well characterized. The crystallographic data, magnetic measurement, IR, EPR and theoretical calculation results demonstrate that complex 1 is the first example of mixed spin Ru -based complex with uncommon electronic configurations of S=1/2 for the cyanido-C bound Ru and S=3/2 for the cyanido-N bound Ru . This phenomenon can be understood by the theoretical calculation results that from the precursor Ru (μ-ap) (CN) (S=3/2) to complex 1 the energy gap between π* and δ* orbitals of the cyanido-C bound Ru core increases from 0.

The MMCT excited state of a localized mixed valence cyanido-bridged Ru-Ru-Ru complex.

To investigate MMCT excited states of MV complexes, two symmetrical tetranuclear cyanido-bridged localized MV complexes RuIICNRuIII,III2NCRuII have been designed and synthesized. The ultrafast time-resolved transient absorption (TA) spectroscopy experiment reveals that the MMCT rate of 1 and 2 is 0.18 × 1014 s-1 (τ = 5.

Influence of ligand substitution at the donor and acceptor center on MMCT in a cyanide-bridged mixed-valence system.

We detail the rational design of bimetallic cyanide-bridged complexes [TpmRu(L)(μ-CN)Ru(L)Cp*][PF] (Tpm = Tris(1-pyrazolyl)methane, L = 1,10-phenanthroline (phen), 2,2'-bipyridine (bpy), 4,4'-dimethyl-2,2'-bipyridine (dbpy), L = bis(diphenylphosphino)methane (dppm), bis(diphenylphosphino)ethane (dppe), Cp* = 1,2,3,4,5-pentamethylcyclopentadiene). The metal-to-metal charge transfer (MMCT) properties of these one-electron oxidized complexes were investigated, suggesting that the substitution of the ancillary ligand provides a strong impetus to systematically tune the MMCT properties. The investigation results indicate that all the mixed-valence complexes belong to Class II mixed-valence complexes, according to the Robin-Day classification.

Different Degrees of Electron Delocalization in Mixed Valence Ru-Ru-Ru Compounds by Cyanido-/Isocyanido-Bridge Isomerism.

The two stable pairs of trimetallic compounds trans-[Cp*(dppe)Ru(μ-NC)Ru(dmap) (μ-CN)Ru(dppe)Cp*][PF ] (1[PF ] , n=2, 3; Cp*=1,2,3,4,5-pentamethylcyclopentadiene; dppe=1,2-bis-(diphenylphosphino)ethane; dmap= 4-dimethylaminopyridine) and trans-[Cp*(dppe)Ru(μ-CN)Ru(dmap) (μ-NC)Ru(dppe)Cp*][PF ] (2[PF ] , n=2, 3), which demonstrate cyanide/isocyanide isomerism, have been synthesized and fully characterized. 1 [PF ] and 2 [PF ] are the one-electron oxidation products of 1 [PF ] and 2 [PF ] , respectively. The results suggest that 1[PF ] is a class III mixed valence compound, whereas 2[PF ] might be an unusually symmetrical class II-III mixed valence compound composed of the two asymmetrical delocalized Ru -NC-Ru mixed valence subunits.

Redox-induced switch between luminescence and magnetism in a trinuclear cyanide-bridged compound.

A trinuclear cyanide-bridged luminescent compound, trans-RuII(DMAP)4(CN)2[(PY5Me2)Mn]2[PF6]4 (1-R), and its oxidation product, ferromagnetic trans-RuIII(DMAP)4(CN)2[(PY5Me2)Mn]2-[PF6]5 (1-O), were synthesized and fully characterized. This is the first example of a molecular material showing a redox-controlled transformation between fluorescence and ferromagnetism.

Introduction of Red-Green-Blue Fluorescent Dyes into a Metal-Organic Framework for Tunable White Light Emission.

The unique features of the metal-organic frameworks (MOFs), including ultrahigh porosities and surface areas, tunable pores, endow the MOFs with special utilizations as host matrices. In this work, various neutral and ionic guest dye molecules, such as fluorescent brighteners, coumarin derivatives, 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM), and 4-(p-dimethylaminostyryl)-1-methylpyridinium (DSM), are encapsulated in a neutral MOF, yielding novel blue-, green-, and red-phosphors, respectively. Furthermore, this study introduces the red-, green-, and blue-emitting dyes into a MOF together for the first time, producing white-light materials with nearly ideal Commission International ed'Eclairage (CIE) coordinates, high color-rendering index values (up to 92%) and quantum yields (up to 26%), and moderate correlated color temperature values.

Redox effects of low-spin Ru(ii/iii) on slow magnetic relaxation of Ru-Mn(iii) 1D cyanide-bridged complexes.

A new one-dimensional cyanide-bridged complex [Mn(salphen)Ru(DMAP)(CN)](PF) (1) and its oxidized derivative [Mn(salphen)Ru(DMAP)(CN)](PF) (2) have been synthesized and fully characterized. Magnetic measurements showed that 1 shows simple paramagnetism but 2 shows intrachain ferromagnetic interaction with slow magnetic relaxation.

Benzoquinone-bridged Co complexes with different magnetic anisotropy induced by solvent molecules.

The first example of discrete small molecular compounds with different magnetic anisotropy induced by solvent molecules, benzoquinone-bridged Co complexes, [(TPyA)Co(L)]·solvent (L = 2,5-dibromo-3,6-dihydroxy-1,4-benzoquinone, solvent = CHCN and HO), has been prepared and fully characterized.

Effects of Ru(ii/iii) redox on the Co(ii) coordination number and magnetic properties of 1D cyanide-bridged Co-Ru compounds.

A new 1D cyanide-bridged Co-Ru compound, {[trans-Ru(dmap)(CN)Co(dipic)(MeOH)](PF)} (1a) (dmap = 4-dimethylaminopyridine, dipic = pyridine-2,6-dicarboxylate), and its reduced state, [trans-Ru(dmap)(CN)Co(dipic)] (1b) have been synthesized. Upon the Ru center reduction from iii to ii, the MeOH solvent molecule bound to Co(ii) in 1a is expelled. 1a displays ferrimagnetic properties but 1b is only a paramagnetic compound.

A Luminescent Metal-Organic Framework Thermometer with Intrinsic Dual Emission from Organic Lumophores.

A new mixed-ligand metal-organic framework (MOF), ZnATZ-BTB, has been constructed as a luminescent ratiometric thermometer by making use of the intrinsic dual emission at cryogenic temperatures. Its twofold interpenetrated network promotes the Dexter energy transfer (DET) between the mixed organic lumophores. The temperature-dependent luminescent behavior arises from the thermal equilibrium between two separated excited states coupled by DET, which is confirmed by Boltzmann distribution fitting.