Luminescent Zn Research Articles

Hydrothermal Synthesis and Characterization of a Novel 1D Luminescent Zn(II) Framework With 1,4-di-(1,2,4-triazole-4-yl) Benzene

Using the benzene-based bis-triazole ligand 1,4-di-(1,2,4-triazole-4-yl)benzene(L) and corresponding zinc(II) salt, under hydrothermal conditions, a novel luminescent 1D Zn(II) coordination polymer, {[Zn(μ2-L)(H2O)4]SiF6·2H2O}n (1) has been isolated and characterized by single-crystal X-ray diffraction, FT-IR, and luminescent analysis. The crystal crystallizes in the Monoclinic C2/c space group, a = 12.997(5) Å, b = 19.376(4) Å, c = 8.080(6) Å, β = 109.379(18)°, Z = 4. These L ligands adopt the bi-dentate bridging coordination modes to link neighboring Zn(II) ions forming 1D chain structure. Solid state luminescent spectrum of 1 also has been investigated indicating the strong emission band centered at 370 nm. The result also represents a good example of the construction of these highly dimensional luminescent inorganic-organic hybrid frameworks.

Self‐assembly of a luminescent Zn(II) carboxylate with the diamondoid topology

A new coordination polymer [Zn(tdc)(bimb)]n (1) (H2tdc = 3,4‐thiophenedicarboxylic acid, bimb = 1,4‐bis(imidazol‐1ˊ‐yl)butane) has been synthesized under hydrothermal condition. X‐ray single‐crystal diffraction determination reveals that 1 crystallizes in the space group P212121 of orthorhombic crystal system: a = 10.517(2), b = 10.889(2), c = 15.206(3) Å. This compound features a 3D network which can be rationalized as a 4‐connected diamondoid net. Moreover, thermal and photoluminescent properties for 1 have also been investigated.

Near infrared luminescent hexanuclear zinc–lanthanide prisms: Synthesis, structure and luminescent properties

The use of the Schiff-base ligand N,N′-bis(3-methoxysalicylidene)ethylene-1,2-diamine (H2L) and fumarate (fum) enables the construction of the hexanuclear luminescent Zn–Ln complexes [Zn4Ln2L4(fum)2] (NO3)2·3CH3OH (Ln=Nd 1; Yb 2; Er 3; Gd 4). The complexes have been characterized by elemental analysis, FT-IR spectra and ESI mass spectrometer. The single crystal X-ray crystallographic study has been carried out on 1. Luminescent properties of these complexes including UV–Vis absorption spectra, excitation, visible and NIR region emission spectra, and NIR emission lifetime have been determined. The intrinsic near-infrared luminescent quantum yield of 1 and 2 are estimated to be 0.63% and 0.84% calculated from the observed lifetime and the natural lifetime of the lanthanide ions, respectively. Systematic analysis suggests that enhancement of near infrared emission could be observed upon construction of the stable polynuclear structures.

Tunable colors and white-light emission based on a microporous luminescent Zn(ii)-MOF

Metal-organic frameworks (MOFs) are a rapidly growing class of hybrid materials with many multifunctional properties. The permanent porosity plays a central role in the functional properties. In particular, the luminescent MOFs with a permanent porosity have wide applications in guest species recognition and adsorption. In this contribution, we aim to develop tunable colors and white-light luminescence materials by the encapsulation of Ln(3+) species in microporous luminescent MOFs. A semi-rigid trivalent carboxylic acid 1,3,5-tri(4-carboxyphenoxy)benzene (H3TCPB) was selected as the organic building block, not only because it is suitable to construct microporous frameworks, but also by reason of its blue luminescent emission. Under solvothermal reactions, a microporous MOF material, [Zn3(TCPB)2(H2O)2]·2H2O·4DMF (JUC-113, JUC = Jilin University, China), was synthesized, which has a permanent porosity and emits blue light. According to three-primary colors, the guest luminescent species should be Tb(3+) and Eu(3+) owing to their distinctive colors (Tb(3+), green; Eu(3+), red). In addition, the luminescent properties of JUC-113 can be easily tuned by different combinations of the encapsulation amount of Tb(3+) and Eu(3+), obtaining white-light emission materials.

Hydrothermal in situ ligand synthesis and self-assembly of a 3D pillar–layer framework with 2-fold interpenetrated pcu topology

A new compound, namely [Zn 1.5 (pbdc)(ATAZ)(OH)] n ( 1 H 2 pbdc = terephthalic acid, HATAZ = 3-amino-1,2,4-triazole), has been obtained by in situ aminotriazole ligand synthesis and characterized by elemental analysis, thermal analysis, as well as single crystal and powder X-ray diffraction analysis. Compound 1 exhibits a 3D pillar–layer framework based on Zn(II)-aminotriazole layers and pbdc pillars, which can be simplified into a 2-fold interpenetrated pcu topological network. Interestingly, two ATAZ ligands and two OH − ligands bridge three Zn(II) ions together, giving rise to a new trinuclear {Zn 3 (ATAZ) 2 (OH) 2 } subunit. In addition, the luminescent and thermal stability properties for the title compound have also been studied. Presented here is a new luminescent Zn(II) coordination polymer, namely [Zn 3 (pbdc)(ATAZ)(OH) 2 ] n ( 1 H 2 pbdc = terephthalic acid, HATAZ = 3-amino-1,2,4-triazole), which was constructed from H 2 pbdc and in situ generated HATAZ ligands. • Hydrothermal in situ HATAZ ligand synthesis • New Zn(II) coordination polymer based on pbdc and ATAZ • It emits intense luminescence at room temperature.

Isomeric luminescent Zn(II) coordination polymers based on pyridinecarboxylate and 5-methyl-1H-tetrazole ligands

Two new metal–organic frameworks, namely [Zn(nic)(mtz)]n (1) and [Zn(isonic)(mtz)]n (2) (Hnic=nicotinic acid, Hisonic=isonicotinic acid, Hmtz=5-methyl-1H-tetrazole), have been obtained through the solvothermal reactions of Zn(NO3)2, Htmz and Hnic or Hisonic. Single crystal X-ray diffraction analysis reveals that compound 1 features a 2D layered structure with sql topology, which is further extended into a 3D supramolecular framework via weak CH…π interactions, and compound 2 is 2-fold interpenetrated 3D framework with dia topology. Luminescent investigation shows that both of them emit blue luminescence at room temperature.

Synthesis, structure and luminescent property of a new Zn(II) coordination polymer with isolated tetrahedral {Zn4O} clusters as building subunits

Abstract A new luminescent Zn(II) coordination polymer, namely [Zn4(L)2(μ4-O)(H2O)2(DMF)]n (1 H3L = biphenyl-3,4,5-tricarboxylic acid, DMF = N,N′-dimethyl formamide) has been synthesized by combining the H3L ligand with Zn(II) salts under solvothermal conditions. Single-crystal X-ray diffraction analysis reveals that 1 features μ4-oxygen-bridged tetrahedral {Zn4O} clusters as building subunits, which are further bridged by L3 − ligands into a complicated three-dimensional (3D) architecture. Topological analysis reveals that it can be reduced into a (3, 6)-connected topological network with the schlafli symbol of {4 · 62}2{42 · 69 · 84}. In addition, the luminescent property of 1 was also investigated in the solid state at room temperature.

Polycatenated Bilayer Structure Containing Honeycomb-like 63 Layers

A new luminescent Zn(II) compound, [Zn2(IN)3(bpy)0.5(CH3COO)]·2(DMA) (1, IN = isonicotinate, bpy = 4,4′-bipyridine, DMA = N,N-dimethylacetamide), was synthesized under solvothermal condition and structurally characterized by single crystal X-ray diffraction. Compound 1 features a (3,4)-connected bilayer structure with honeycomb-like 63 layers and bpy pillars. Each individual bilayer is catenated with two adjacent bilayers, giving rise to a rare 2D + 2D → 3D polycatenation motif.

Hydrothermal synthesis and characterization of a series of luminescent Zn(ii) and Cd(ii) coordination polymers with the new versatile multidentate ligand 1,3-di-(1,2,4-triazol-4-yl)benzene

Used a newly designed multidentate benzene-based bis-triazole ligand 1,3-di-(1,2,4-triazol-4-yl)benzene (L), a series of luminescent Zn(II) and Cd(II) coordination polymers, namely, {[Zn(μ2-L)2(H2O)2]·(SiF6)·H2O}n (1), {[Cd(μ2-L)2(H2O)2]·(SiF6)·2H2O}n (2), {[Zn(μ2-L)Br2]·H2O}n (3), {[Cd(μ2-L)2(NCS)2]·2H2O}n (4), {[Cd(μ2-L)(μ4-L)](BF4)2}n (5), {[Cd(μ2-L)(μ4-L)](ClO4)2}n (6) and {[Cd3(μ3-L)6](NO3)6}n (7) have been isolated under hydrothermal conditions. Both 1 and 2 present 1D double chain structures, which contain two kinds of different supramolecular channels. For 3, zinc(II) ions are linked by L ligands and arranged into infinite right- or left-handed helical chains. 4 presents a 2D framework in which 1D right-handed and left-handed helical structures are interlinked via Cd(II) centers as hinges. 5 and 6 respectively contain μ2- and μ4-L ligands in triazole–metal complexes. These μ4-L ligands link neighboring Cd(II) centers forming a 2D network containing infinite {Cd-(trz)2-Cd}n chains, which is quite different from the 2D arrangement in 4. 7 presents a novel 3D porous MOF (porous metal–organic framework) containing triangular nano-porous channels with edges of 13.622 A, in which free NO3− anions are located. Anion exchange experiments based on 7 also indicate that NO3− anions are able to be exchanged with ClO4− anions in the solid state. Both the dihedral angles (between two triazole rings or between triazole and aromatic benzene rings) for L are flexible and ultimately tune the coordination geometries in constructing various different coordination polymers. For 1–7 the comparison between powder X-ray diffraction (PXRD) and a simulated analysis from crystal data confirmed the pure crystal phases. Solid-state luminescent properties and thermal stabilities of 1–7 also have been determined.

Anion dependent self-assembly of luminescent Zn–Ln (Eu and Tb) salen complexes

Four Zn-Ln salen complexes are formed with the Schiff base ligand bis(3-methoxysalicylidene)ethylene-1,2-phenylenediamine (H2L). The complexes are trinuclear [LnZn2L2(OAc)2]·CF3SO3·Et2O (Ln = Eu (1) and Tb (2)), and dinuclear [EuZnL(OAc)(NO3)2MeOH] (3) and [TbZnL(OAc)2(NO3)] (4). The structures of 1–4 were determined by single crystal X-ray crystallographic studies and the respective luminescence properties in MeCN solution were determined.

Hetero-binuclear near-infrared (NIR) luminescent Zn–Nd complexes self-assembled from the benzimidazole-based ligands

With the compound [Zn(HL1)2(Py)] (H2L1=2-(1H-benzo[d]imidazol-2-yl)-6-methoxyophenol), Py=pyridine) or [Zn(HL2)2(Py)] (H2L2=2-(1H-benzo[d]imidazol-2-yl)-4-bromo-6-methoxyphenol) as the precursor, complexes [ZnLn(HL1)2(Py)(NO3)3] (Ln=Nd, 1; Ln=Gd, 2) or [ZnLn(HL2)2(Py)(NO3)3] (Ln=Nd, 3; Ln=Gd, 4) were obtained by the further reaction with Ln(NO3)3·6H2O (Ln=Nd or Gd). The result of their photophysical properties shows that the strong and characteristic near-infrared (NIR) luminescence of Nd3+ ions for complexes 1 and 3 with emissive lifetimes in microsecond range, has been sensitized from the excited state (1LC and 3LC) of the benzimidazole-based ligands, and the involvement of heavy atoms (Br) at the ligand endows the enhanced NIR luminescent property.

Construction and NIR luminescent property of hetero-bimetallic Zn–Nd complexes from two chiral salen-type Schiff-base ligands

Two new near-infrared (NIR) luminescent Zn–Nd complexes [ZnL 1Nd(OAc)(NO 3) 2] ( 3) and [ZnL 2Nd(DMF) 2(NO 3) 3] ( 4) have been obtained with two salen-type Schiff-base ligands H 2L 1 and H 2L 2 , ( H 2L 1 = N, N′-bis(3-methoxysalicylidene)-(1s, 2s)-(−)1,2-dipheneylethylenediamine and H 2L 2 = N, N′-bis(3-methoxysalicylidene)-(s)-2,2-diamine-1,1′-binaphthyl) from the reaction of different chiral diamines with o-vanillin. The X-ray crystal structure analysis reveals that both of them crystallize in the chiral space groups with P2(1), a = 10.1669(6), b = 19.3775(11), c = 17.4639(10) Å, β = 94.8710(10)°, V = 3428.1(3) Å 3, Z = 4 for 3, and C2, a = 22.1914(13), b = 9.7886(6), c = 22.0138(13) Å, β = 118.9590(10)°, V = 4372.5(4) Å 3, Z = 4 for 4. Complexes 3– 4 are both dinuclear Zn–Nd structures, while suitable choice of chiral Schiff-base ligands could induce the different complexions of ligands and metal ions, and the functional control of ligand character shows a potentially effective way to the fine-tuning properties of NIR luminescence from Nd ions.

The synthesis, crystal structure and spectroscopic properties of luminescent Zn(II) complex

A luminescent Zn(II) complex 1, ZnL 2Cl 2·2H 2O has been synthesized where L = 2,2′,2″-(1,3,5-benzenetriyltrimethylidyne) as a yellow crystal. Single crystal X-ray analysis of the compound 1 shows a distorted tetrahedral structure. The compound 1 crystallizes in monoclinic, space group C2/ c with a = 20.3151(19), b = 8.7299(9), c = 24.626(2) Å, β = 107.474(2)°, V = 4165.9(7) Å 3. At room temperature, the complex 1 exhibits an intense blue emission at 474 nm upon 380 nm excitation.

The synthesis and crystal structures of new 2-aminomethylbenzimidazole Zinc(II) complexes exhibiting luminescence

Two new blue luminescent Zn(II) complexes, [ZnL2(H2O)]Cl2 · H2O (1) and [ZnL2Cl][ZnLCl2] · NO3 (2) (L = 2-aminomethylbenzimidazole) have been synthesized and characterized spectroscopically and crystallographically. The structure of complex (1) can be described as a square pyramid. In the complex (2), there are two units [ZnLCl2] (a), and [ZnL2Cl]+ (b), which have a distorted tetrahedral geometry and a slightly distorted trigonal bipyramidal coordination geometry, respectively. In these complexes, significant multiple inter- and intra-molecular hydrogen bonding and π–π stacking interactions are shown. These contacts lead to aggregation and supramolecular assembly of complexes (1) and (2) into 3D and 2D frameworks, respectively. Fluorescent analysis in the dilute DMF solution and solid state shows that both complexes exhibit intense emission in blue region. They display high blue luminescence quantum efficiency due to a metal-to-ligand charge transfer (MLCT) and have a bathochromic shift of the emission energy compared with the free ligand L. The emission intensity of complex (2) is higher than that of complex (1).

Supramolecular Host−Guest Systems of Luminescent Zn(II) Complexes with Benzene, Nitrobenzene, and Ethanol: Selectivity of Guest Inclusion and Solid-State Fluorescence Modulation Studies

The luminescent Zn(II) complex [Zn(phen)(aba)2] (B) {phen = 1,10-phenanthroline, aba = 4-(dimethylamino)benzoate} crystallizes as [Zn(phen)(aba)2(H2O)] (B1) from moist solvents. Compound B shows high selectivity toward benzene in the presence of other organic guests in solution as well as in the vapor phase forming {[Zn(phen)(aba)2(H2O)]·1/2C6H6}n (1). Compound 1 assumes a channel structure where benzene molecules are trapped in alternate channels via various supramolecular interactions. Compound B1, on the other hand, does not show any selectivity toward guest inclusion and readily assembles as {[Zn(phen)(aba)2(H2O)]·2C6H5NO2}n (2) in the presence of nitrobenzene or as {[Zn(phen)(aba)2(H2O)]·2C2H5OH}n (3) in the presence of ethanol. In 2, nitrobenzene molecules form zigzag tapes via C−H···O and C−H···π interactions inside the channels, while the structure of 3 looks like a two-dimensional network with voids occupied by tetrameric ethanol clusters. The three structures exhibit significantly red-shifted emission in the solid state with respect to the parent complex. In the case of 1, the desorption and resorption of benzene are thermally reversible as monitored by X-ray powder diffraction.

Self-Assembly of a Luminescent Zinc(II) Complex: a Supramolecular Host−Guest Fluorescence Signaling System for Selective Nitrobenzene Inclusion

A luminescent Zn(II) complex, [Zn(bpy)(aba)2] (1) {bpy = 2,2'-bipyridyl and aba = 4-dimethylaminobenzoate} has been synthesized as a white solid. Complex 1 shows unusually high selectivity toward nitrobenzene in the presence of other organic guests in solution, as well as in the vapor phase, resulting in both a dramatic color change and a concomitant quenching of luminescence. When crystallized from nitrobenzene, 1 affords deep red crystals with the composition [Zn(bpy)(aba)2] x C6H5NO2 (2) as a hydrogen-bonded channel structure via unusual intermolecular C-H...C(sp3) and H...H interactions. Inside the channels, nitrobenzene molecules form infinite polar linear tapes through strong C-H...O interactions in a head-to-tail fashion. The desorption and resorption of nitrobenzene can be achieved in a thermally reversible manner that can be monitored by X-ray powder diffraction patterns.

Design and synthesis of a near infra-red luminescent hexanuclear Zn–Nd prism

The use of the Schiff-base ligand N,N'-bis(5-bromo-3-methoxysalicylidene)propylene-1,3-diamine (H2L) and 1,4-benzenedicarboxylate (BDC) enables the construction of the hexanuclear luminescent Zn-Nd complex [Zn4Nd2L4(1,4-BDC)2].[Nd(NO3)5(H2O)].Et2O.2EtOH.3H2O.

Design and syntheses of blue luminescent zinc(II) and cadmium(II) complexes with bidentate or tridentate pyridyl-imidazole ligands

A series of luminescent Zn(II) and Cd(II) complexes have been prepared based on three different π-conjugated ligands, 2-(2-pyridyl)-imidazole (HL1), 2-(2-pyridyl)-benzimidazole (HL2) and 2,6-bis(benzimidazol-2yl)-pyridine (H 2L3). The PL spectra of the ligands exhibit a bathochromic shift in agreement with the extended π-conjugation of the ligand. The spectra of the complexes with the ligands follow the same rule. The structures of Zn(L2) 2H 2O ( 5), [Cd(L2) 2(H 2O) 2] · 2DMSO ( 6), Zn(HL3) 2 ( 9) and Cd(HL3) 2 ( 10) have been established by X-ray crystallography. The structure of 5 can be best described as a square pyramid. The coordination geometries of 6, 9 and 10 can be described as distorted octahedrons. In the solid state and in DMSO, these complexes show emission maxima in the blue region. The complexes have a bathochromic shift of the emission energy in sharp contrast to the free ligands. They display blue luminescence and have high luminescence quantum efficiency. A theoretical study reveals that the emissions are assigned to intraligand transitions of the deprotonated L2 and HL3 ligands, and the metal ions in the complexes play a key role in stabilizing the ligand and promoting the luminescence, which is consistent with the experimental results.

Synthesis and structures of two luminescent Zn(II) complexes with pyrazole and carboxylate ligands

Two new Zn(II) complexes with pyrazole and carboxylate ligands, [Zn(μ-pz)(pzH)(O2CCH2CH3)]2 (pzH = pyrazole), 1 and [Zn(bet)2(pzH)2](ClO4)2 (bet = Me3NCH2CO2), 2, were prepared and structurally characterized. Both compounds exhibit blue emission at room temperature in solid state.

In situ spectral control of Zn species during helicon-wave-excited-plasma sputtering epitaxy of ZnO

Atomic species in the sputtered plumes from undoped ZnO target were identified by means of emission spectroscopy during helicon-wave-excited-plasma sputtering epitaxy. Luminescent Zn species were found to be excited neutral zinc (Zn*) and zinc cations (Zn+*), and Zn* density was independently controlled by the target bias (Vt) that accelerates the velocity of Ar cations while keeping the plasma density constant. The ZnO film formation seemed to have certain threshold Vt (around −200 V at 600 °C), and the growth rate increased with the magnitude of Vt but decreased with the substrate temperature, indicating that the growth rate is limited by the sticking coefficient of Zn. As a result of the supply mode of Zn that is similar to the case for laser molecular-beam epitaxy, the epitaxial (0001) ZnO on (112̄0) sapphire substrate had ultra-smooth surfaces having atomically flat terraces, and exhibited excitonic reflectance anomalies and luminescence peaks at low temperature.