Intermolecular interactions, photocatalysis and THz-TDS interrelationships for lanthanide phosphine oxide complexes based on {PW12}.

A series of rare earth complexes containing (α-PW12O40)3- and PO ligand are synthesized by water bath in 70 °C, [Ln(OPPh3)4(H2O)3](PW12O40)·4CH3CN (Ln = La, Pr, Nd, Sm, Gd, Tb, Ho 1-7) (OPPh3 = Triphenylphosphine oxide, {PW12} = phosphotungstic acid). The precise structures are confirmed by X-ray single crystal diffraction and the result shows all complexes are isostructural. Complexes 1-7 are fully characterized by PXRD, FT-IR, TGA, UV diffuse reflectance spectra and terahertz time-domain spectroscopy (THz-TDS). Complex 3 exhibits the highest photocatalytic degradation efficiency for methylene blue (MB) in this series of complexes. The experimental results showed that the photodegradation efficiency can remain constant at the level of 95% after five consecutive cycles. The photocatalytic reaction kinetics and mechanism of complexes were investigated. Additionally, complexes also exhibit photocatalytic hydrogen evolution activity. THz-TDS was used to characterize the complexes and its raw materials, the characteristic peaks of OPPh3 (broad peak at 1.20 THz) and phosphotungstic acid (sharp peaks at 0.23, 0.32 THz) were obtained.

Facile high yield, excellent catalytic performance of polyoxometalate-based lanthanide phosphine oxide complexes: Syntheses, structures, photocatalysis and THz spectra.

Water pollution, which continuously threatens human health and the sustainable development of society, has become a major concern. Photocatalytic degradation is an effective strategy to remove organic dyes from wastewater. For this strategy, it is crucial to select the appropriate catalyst. Using triphenylphosphine oxide (OPPh3) as the ligand, phosphomolybdic acid as the anion template, three new lanthanide complexes [Ln(OPPh3)4(H2O)3](PMo12O40)∙4C2H5OH (1-3) (Ln = Sm, Gd, Tb) were synthesized. The raw materials for the reaction are cheap and readily available. The convenient synthesis method is environmentally friendly, with high yield (70%-80%). Complexes 1-3 are all seven-coordinated mononuclear structures centered on lanthanide ions, [PMo12O40]3- anions and solvent molecules are not coordinated with metal ions. These mononuclear structures eventually form complicated 3D supramolecular structures through hydrogen bonds, Mo-O … π or C-H … π weak interactions. Complexes 1-3 photocatalytic degradation of MB have high removal rates, as catalysts have enough stability to be reused, and can be used as excellent catalysts for the degradation of dye molecules in sewage. Among them, the removal rate of MB by photodegradation of complex 2 was highest (99.50%). In addition, the effects of different initial concentrations of MB solution and different types of organic dyes on the photocatalysis experiment were investigated. The photocatalytic reaction mechanism of complexes 1-3 was also studied. Due to the similar structures of complexes 1-3, they have almost the same THz absorption spectra with different absorption intensity, which may be attributed to the difference of the number of weak interactions. Therefore, terahertz spectroscopy can be used as a sensitive method to distinguish and determine small differences between lanthanide-organic complexes. This is the first time that this spectrum has been used to characterize lanthanide phosphine oxide complexes modified by [PMo12O40]3-.

Photo-induced variation of magnetism in coordination polymers with ligand-based electron transfer.

Photo-induced variation of magnetism from ligand-based electron transfer has been extensively studied because of its potential applications in magneto-optical memory devices, light-responsive switches, and high-density information storage materials. In this review, we discussed the progress in the photo-induced variation of magnetism in coordination polymers with ligand-to-metal charge transfer (LMCT), ligand-to-ligand charge transfer (LLCT) and internal ligand charge transfer (ILCT), which provides fundamentals for the rational design of multi-functional materials. We also discussed the design and synthetic strategy of such molecule-based materials and gave views on the current challenges and growth trends in this field.

A new application of terahertz time-domain absorption spectra in luminescent complexes: characterization of the C-Hπ weak interactions in Cu(I) complexes.

Six Cu(i) complexes, [Cu(2,3-f)(bdppmapy)]BF4 (1), [Cu(2,3-f)(bdppmapy)]ClO4 (2), [Cu(2,3-f)(bdppmapy)]CF3SO3 (3), [Cu(imidazo[4,5-f])(bdppmapy)]BF4 (4), [Cu(imidazo[4,5-f])(bdppmapy)]ClO4 (5), and [Cu(imidazo[4,5-f])(bdppmapy)]CF3SO3·MeOH (6·MeOH) (bdppmapy = N,N-bis[(diphenylphosphino)methyl]-2-pyridinamine, 2,3-f = pyrazine[2,3-f][1,10]-phenanthroline, and imidazo[4,5-f] = 1H-imidazo[4,5-f][1,10]-phenanthroline), have been synthesized to explore the effects of counteranions on their crystal structures, photophysical properties, and terahertz (THz) spectra. Time-dependent density functional theory (TD-DFT) shows that the luminescence performance of these complexes is attributed to the metal-to-ligand charge transfer (MLCT) in combination with ligand-to-ligand charge transfer (LLCT). In complexes 1-3, the characteristic peak at 1.4 THz is mainly related to the C-Hπ interaction formed by the H atom on the 4#/5# position of 2,3-f and the benzene ring from the bdppmapy on the adjacent asymmetric unit. The common C-Hπ interaction enhances the rigidity of the structure and has non-negligible influence on the photoluminescence quantum yields (PLQYs): the stronger the C-Hπ interaction is, the higher the quantum yield (QY) is. In complexes 4-6, similar absorption peaks (1.10-1.30 THz) are mainly related to the C-Hπ interactions, and strong absorption peaks (1.50-1.90 THz) are affected by the typical hydrogen bonds N-HF/O and O-HO. These results show that some weak interactions can be characterized by THz time-domain spectroscopy (THz-TDS). So, the THz spectroscopy method would make it possible to tune some of the weak interactions in complex structures to regulate the luminescence of materials.

Terahertz time-domain absorption spectra of Cu(I) complexes bearing tetraphosphine ligands: the bridge between the C-Hπ and ππ interactions and photoluminescence properties.

The synthesis of four heteroleptic dinuclear Cu(i) complexes bearing tetraphosphine and diimine ligands was reported. Complexes 1-3 were successfully obtained through microwave synthesis while complex 4 was synthesized through traditionally stirring at room temperature. These complexes are listed as follows: [Cu2(Dpq)2(dppeda)](ClO4)2·1.5CH2Cl2 (1), [Cu2(neo)2(dppeda)](ClO4)2·1.3CH2Cl2·1.7C4H10O (2), [Cu2(batho)2(dppeda)](ClO4)2·C4H10O (3), and [Cu2(batho)2(dpppda)](ClO4)2·3CH2Cl2 (4) {(Dpq = pyrazino[2,3-f][1,10]phenanthroline, batho = 4,7-diphenyl-1,10-phenanthroline, neo = 2,9-dimethyl-1,10-phenanthroline, dppeda = N1,N1,N2,N2-tetrakis[(diphenylphosphino)methyl]-1,2-ethanediamine, and dpppda = N1,N1,N4,N4-tetrakis[(diphenylphosphino)methyl]-1,4-benzenediamine}. Their crystal structures have been elucidated by X-ray crystallography and their photophysical properties have been investigated in detail. Photophysical studies and time domain density functional theory (TD-DFT) calculations show that the luminescence performance of these four complexes is ascribed to metal-to-ligand charge transfer (MLCT) mixed with ligand-to-ligand charge transfer (LLCT), and complex 2 shows green emission at 574 nm with the highest quantum yield of up to 52.80%. In addition, the research of photoluminescence properties under the guidance of terahertz spectroscopy technology leads to the preliminary discovery of a correlation between crystal packing and luminescence. It is found that the terahertz spectrum and absorption peak are strongly interdependent on C-Hπ and ππ interactions, and the external weak interactions have negative effects on the luminescence performance. Herein, we predict that the terahertz spectroscopy analysis establishes a bridge between weak interactions (C-Hπ and ππ interactions) and the photoluminescence properties, and puts forward a problem that should be noticed in designing Cu(i) complexes.

6-Nitro-1,3-benzothia-zole-2(3H)-thione.

In the title mol-ecule, C(7)H(4)N(2)O(2)S(2), the nitro group is twisted by 5.5 (1)° from the plane of the attached benzene ring. In the crystal, N-H⋯S hydrogen bonds link pairs of mol-ecules into inversion dimers, which are linked by weak C-H⋯O inter-actions into sheets parallel to (101). The crystal packing exhibits short inter-molecular S⋯O contacts of 3.054 (4) Šand π-π inter-actions of 3.588 (5) Šbetween the centroids of the five- and six-membered rings of neighbouring mol-ecules.

Iodido[5-methyl-1H-benzimidazole-2(3H)-thione-κS]bis-(triphenyl-phosphane-κP)copper(I) methanol monosolvate.

In the title compound, [CuI(C(8)H(8)N(2)S)(C(18)H(15)P)(2)]·CH(3)OH, the coordination environment around the Cu(I) atom is distorted tetra-hedral, defined by two P atoms of two triphenyl-phosphane ligands, one S atom of a 5-methyl-1H-benzimidazole-2(3H)-thione ligand and one I atom. The complex mol-ecules and the methanol solvent mol-ecules are connected via N-H⋯O and O-H⋯I hydrogen bonds, forming a chain along [010]. An intra-molecular N-H⋯I hydrogen bond is also observed.

3-Amino-1H-1,2,4-triazole-5(4H)-thione-4,4'-bipyridine (1/1).

The title two-component mol-ecular crystal, C(10)H(8)N(2)·C(2)H(4)N(4)S, was obtained unexpectedly by reaction of Zn(NO(3))(2)·6H(2)O, NH(4)BF(4) with 3-amino-1,2,4-triazole-5-thione (3-AMT) and 4,4'-bipyridine in water. The dihedral angle between the pyridine rings in the 4,4'-bipyridine molecule is 17.00 (13)°. In the crystal, N-H⋯N and N-H⋯S hydrogen bonds between the components lead to the formation of a three-dimensional network. Furthermore, the structure features face-to-face π-π stacking inter-actions between the 4,4'-bipyridine and triazole rings, with a centroid-centroid distance of 2.976 (2) Å.

catena-Poly[[[diaqua-(1,10-phenanthroline-κ(2)N,N')zinc]-µ-4,4'-bipyridine-κ(2)N:N'] dinitrate 4,4'-bipyridine hemisolvate monohydrate].

In the title compound, [Zn(C(10)H(8)N(2))(C(12)H(8)N(2))(H(2)O)(2)](NO(3))(2)·0.5C(10)H(8)N(2)·H(2)O, the Zn(II) atom is coordinated in a distorted octa-hedral geometry by two N atoms from two 4,4'-bipyridine (4,4'-bipy) ligands, two N atoms from a chelating 1,10-phenanthroline ligand and two O atoms from two mutually cis water mol-ecules. The 4,4'-bipy ligands bridge the Zn(II) atoms into a chain structure along [100]. The uncoordinated 4,4'-bipy mol-ecule lies on an inversion center. O-H⋯O and O-H⋯N hydrogen bonds connect the cationic chains, the nitrate anions, the uncoordinated 4,4'-bipy mol-ecules and the water mol-ecules into tow-dimensional networks.

Bis[µ-bis-(diphenyl-phosphan-yl)methane-κ(2)P:P']bis-[(isoquinoline-κN)silver(I)] bis-(trifluoro-methane-sulfonate)-isoquinoline (1/1).

The title complex, [Ag(2)(C(25)H(22)P(2))(2)(C(9)H(7)N)(2)](CF(3)SO(3))(2)·C(9)H(7)N, was prepared by the reaction of silver(I) trifluoro-methane-sulfonate with isoquinoline and bis-(diphenyl-phosphan-yl)methane (dppm). The dinuclear mol-ecule is located about a center of inversion and the Ag(I) atom is coordinated by two dppm P atoms and one isoquinoline N atom, forming an eight-membered metalla ring. In addition, in the asymmetric unit, there is a half-mol-ecule of isoquinoline located about a center of inversion. Since this mol-ecule does not possess this symmetry, for one position in the ring there is superposition of both a C atom of a C-H group and the isoquinoline N atom. In the structure, the Ag-P distances [2.4296 (9) and 2.4368 (9) Å] agree with the corresponding distances in related structures, while the Ag-N bond length [2.489 (3) Å] is slightly longer than that in related structures. On the other hand, the P-Ag-P angle [156.44 (3)°] is much larger than the corresponding angles in related structures. The trifluoro-methane-sulfonate anions do not coordinate to Ag(I) atoms. As is usually found for these anions, the -CF(3) group is disordered over two orientations [occupancies = 0.57 (12) and 0.43 (12)].

Tetra-kis(triphenyl-phosphane-κP)silver(I) tetra-fluorido-borate.

The title complex, [Ag(C(18)H(15)P)(4)]BF(4), was prepared by the reaction of silver(I) tetra-fluorido-borate and triphenyl-phosphane in the presence of 1,2-bis-(pyridin-2-yl)ethyl-ene. The Ag(I) atom is tetra-hedrally coordinated by four P atoms from triphenyl-phosphane (PPh(3)) ligands. Due to symmetry, the tetra-fluorido-borate anion is disordered over three positions (each with one third occupancy). The tetra-fluorido-borate anion does not coordinate to the Ag(I) atom.

catena-Poly[[(isoquinoline-κN)(triphenylphospane-κP)copper(I)]-µ-thio-cyanato-κN:S].

In the title coordination compound, [Cu(NCS)(C(9)H(7)N)(C(18)H(15)P)](n), the Cu(I) atom is tetra-hedrally coordinated by one N atom from an isoquinoline ligand, one P atom from a triphenyl-phospane ligand, and one N and one S atom from two thio-cyanate anions. The thio-cyanide anions bridge the Cu(I) atoms into a chain along [100]. π-π inter-actions between the pyridine and benzene rings of the isoquinoline ligands connect the chains [centroid-to-centroid distance = 3.722 (3) Å].

5,6-Dimethyl-1,2,4-triazin-3-amine.

In the crystal structure of the title compound, C(5)H(8)N(4), adjacent mol-ecules are connected through N-H⋯N hydrogen bonds, resulting in a zigzag chain along [100]. The amino groups and heterocyclic N atoms are involved in further N-H⋯N hydrogen bonds, forming R(2) (2)(8) motifs.

4,4'-Bipyridine-1,1'-diium bis-(1,3-benzo-thia-zole-2-thiol-ate).

In the title salt, C10H10N2(2+)·2C7H4NS2(-), the complete 4,4'-bipyridine-1,1'-diium dication is generated by a center of symmetry. In the crystal, N-H⋯N hydrogen bonds are observed between the cations and anions.

[Bis[µ-bis-(diphenyl-phosphino)methane-1:2κ(2)P:P']-bis-(nitrito-κ(2)O,O')]disilver(I) acetonitrile disolvate.

The title complex, [Ag(2)(NO(2))(2)(C(25)H(22)P(2))(2)]·2CH(3)CN, is a centrosymmetric dimer in which two bis(diphenylphosphino)methane ligands bridge two Ag(+) ions, forming an eight-membered ring with a short Ag⋯Ag separation of 3.1809 (5) Å. The distorted P(2)O(2) coordination of the cation is completed by two O-donors from a symmetric bidentate chelate NO(2) (-) anion [Ag-O = 2.550 (3) and 2.567 (3) Å].

4,4'-Bipyridine-3,3'-disulfanediyl-bis-(1H-1,2,4-triazole-5-amine) (1/1).

In the title 1:1 adduct, C(10)H(8)N(2)·C(4)H(6)N(8)S(2)·, the components are connected through N-H⋯N hydrogen bonds, leading to a two-dimensional structure. The C-S-S-C torsion angle is -83.6 (1)°. The dihedral angle between pyridine rings is 1.86 (15)°.

[1,3-Bis(diphenyl-phosphan-yl)propane-κP,P'](1,10-phenanthroline-κN,N')copper(I) perchlorate.

The title compound, [Cu(C(12)H(8)N(2))(C(27)H(26)P(2))]ClO(4), crystallizes with two Cu(I) complex cations and two perchlorate anions in the asymmetric unit. Each Cu(I) cation is four-coordinated by two P atoms of a 1,3-bis-(diphenyl-phosphan-yl)propane mol-ecule and two N atoms of a 1,10-phenanthroline ligand, with a coordination geometry that can be considered as distorted tetra-hedral. The crystal studied was twinned with a twin ratio of 0.786 (2):0.214 (2).

An ortho-rhom-bic polymorph of pyrazino-[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile.

The title compound, C(16)H(6)N(6), is a polymorph of the previously reported structure [Kozlov & Goldberg (2008 ▶). Acta Cryst. C64, o498-o501]. Unlike the previously reported monoclinic polymorph (space group P2(1)/c, Z = 8), the title compound reveals ortho-rhom-bic symmetry (space group Pnma, Z = 4). The mol-ecule shows crystallographic mirror symmetry, while the previously reported structure exhibits two independent mol-ecules per asymmetric unit. In the title compound, adjacent mol-ecules are essentially parallel along the c axis and tend to be vertical along the b axis with dihedral angles of 72.02 (6)°. However, in the reported polymorph, the entire crystal structure shows an anti-parallel arrangement of adjacent columns related by inversion centers and the two independent mol-ecules are nearly parallel with a dihedral angle of 2.48 (6)°.

Tetra-kis(triphenyl-phosphane-κP)silver(I) trifluoro-methane-sulfonate dichloro-methane monosolvate.

In the title compound, [Ag(C(18)H(15)P)(4)]CF(3)O(3)S·CH(2)Cl(2), the Ag atom is coordinated by four P atoms from four PPh(3) ligands. The P-Ag-P angles are in the range 108.02 (6)-110.15 (6)°, which confirms the distorted tetra-hedral environment around the Ag atom.

Tris(3-amino-5,6-dimethyl-1,2,4-triazine-κN)silver(I) trifluromethane-sulfonate-3-amino-5,6-dimethyl-1,2,4-triazine (1/1).

The asymmetric unit of the title compound, [Ag(C(5)H(8)N(4))(3)](CF(3)O(3)S)·C(5)H(8)N(4), contains two cations, two anions and two uncoordinated 3-amino-5,6-dimethyl-1,2,4-triazine (admt) ligands. It was prepared from the reaction of silver trifluoro-methane-sulfonate and admt in a 2:3 molar ratio. Both silver(I) ions are bonded to three admt mol-ecules via their 2-position triazine N atoms in almost regular trigonal-planar geometries. Three intra-molecular N-H⋯N hydrogen bonds between adjacent admt mol-ecules in each cation help to maintain their overall near planarities (r.m.s. deviations for the 28 non-H atoms = 0.139 and 0.153 Å). In the crystal, numerous N-H⋯N, N-H⋯O, C-H⋯O, C-H⋯N and C-H⋯F hydrogen-bonding interactions link the components into a three-dimensional network.