A Dual Associated-Functional Fluorescent Switch: From Alternate Detection Cycle for Fe(III) and pH to Molecular Logic Operations.

With the expansion and deepening of scientific research, dual-functional or multifunctional materials are urgently needed to replace those for single application. Herein, a fluorescence sensing system based on an In(III)-organic complex with in situ Lewis acid sites has been constructed, exhibiting high sensitivity for the detection of Fe(III) ions with a low detection limit of 3.95 µM and a short response time of within 10 s. It is noteworthy that the quenched fluorescence of the Fe(III)-incorporated sample could be reopened linearly with an increase of alkalinity, followed by the reactivation of its functionality to identify Fe(III) ions, forming an alternate detection cycle for Fe(III) and pH with off-on-off fluorescent switch characteristics. Considering its unique molecular recognition capability, an advanced three-input (Fe(III), EDTA, and OH-) and two-output (B440 and G489) Boolean logic operation comprising BUFF, NOT, OR, and AND logic gates was integrated, possessing potential applications in intelligent multianalyte sensing systems.

Thermally-induced single-crystal-to-single-crystal transformations from a 2D two-fold interpenetrating square lattice layer to a 3D four-fold interpenetrating diamond framework and its application in dye-sensitized solar cells.

In this work, a rare 2D → 3D single-crystal-to-single-crystal transformation (SCSC) is observed in metal-organic coordination complexes, which is triggered by thermal treatment. The 2D two-fold interpenetrating square lattice layer [Cd(IBA)2]n (1) is irreversibly converted into a 3D four-fold interpenetrating diamond framework {[Cd(IBA)2(H2O)]·2.5H2O}n (2) (HIBA = 4-(1H-imidazol-1-yl)benzoic acid). Consideration is given to these two complexes with different interpenetrating structures and dimensionality, and their influence on photovoltaic properties are studied. Encouraged by the UV-visible absorption and HOMO-LUMO energy states matched for sensitizing TiO2, the two complexes are employed in combination with N719 in dye-sensitized solar cells (DSSCs) to compensate absorption in the ultraviolet and blue-violet region, offset competitive visible light absorption of I3(-) and reducing charge the recombination of injected electrons. After co-sensitization with 1 and 2, the device co-sensitized by 1/N719 and 2/N719 to yield overall efficiencies of 7.82% and 8.39%, which are 19.94% and 28.68% higher than that of the device sensitized only by N719 (6.52%). Consequently, high dimensional interpenetrating complexes could serve as excellent co-sensitizers and have application in DSSCs.

HONH3Cl optimized CH3NH3PbI3 films for improving performance of planar heterojunction perovskite solar cells via a one-step route.

Planar heterojunction perovskite solar cells (PHJ-PSCs) constructed with one-step precursor solution spin-coating deposition (OPSSD) usually give an extremely low performance mainly due to the poor morphology and low crystallinity of the perovskite films. In this work, by incorporating a suitable HONH3Cl additive in the perovskite precursor solution, a high quality perovskite film with improved morphology and crystallinity was obtained. The UV-vis measurement of the CH3NH3I solutions without and with HONH3Cl demonstrates that the improved quality of the perovskite film can be easily attributed to a combined effect of N2, I2, H2O and CH3NH3Cl originating from the oxidation of CH3NH3I triggered by the HONH3Cl additive, which can manipulate the crystallization process of the perovskite. Accordingly, the improved performance for the HONH3Cl-induced PHJ-PSCs can also be demonstrated. At the optimized molar ratio of 1 : 1 : 0.1 for PbI2 : CH3NH3I : HONH3Cl, the PHJ-PSCs exhibit an average power conversion efficiency (PCE) of 10.61 ± 0.51%, which is much higher than that of pristine 1 : 1 : 0 based cells without additive (7.21 ± 0.61%), and the best performing HONH3Cl-induced device can yield a PCE as high as 11.12% with a Jsc of 18.42 mA cm-2, Voc of 0.95 V and FF of 0.63. Introducing suitable HONH3Cl as an additive into the perovskite precursor solution is really an effective route to enhance the performance of the PHJ-PSCs via OPSSD.

[Study on the Structure and Photoluminescent Properties of Mono-Zn(â ¡) and Di-Cu(â ) Complexes Constructed from Nitrogen Heterocyclic Ring Ligand].

The mononuclear Zn(Ⅱ) complex [Zn(2,6-PDA)(phen)H2O]·H2O (1) and binuclear Cu(Ⅰ) complex{[Cu(µ-Ⅰ)(phen)H2O]·H2O}2 (2) (2,6-H2PDA=2,6- pyridinedicarboxylic acid，phen=1,10- phenanthroline monohydrate) have been prepared with hydro-thermal synthesis method. These complexes have been characterized with single-crystal X-ray, elemental analysis, and IR spectroscopy. The fluorescence spectra of 1 and 2 are studied in solid-state and dimethyl sulfoxide (DMSO) solution. The maximum absorption peak of 1 and 2 are at 253 nm and 242 nm respectively, which are red shift to that of the phen ligand with inceased intensity. It may be assigned to the intraligand π→π* transition of the phen ligand that is modified by the Zn(Ⅱ) or Cu(Ⅰ) ions. On the basis of the coordination, the absorption of organic ligands in the ultraviolet region is increased, which is better for the energy absorption of the ligand. 1 and 2 all showed blue light emission. The emission peak of 1 and 2 have experienced a red shift (ca. 55 and 23 nm) in the solid state (λem = 407, 434, 467 nm for 1, 442, 469, 501 nm for 2) compared to in DMSO solution (λem = 361, 379, 392 nm for 1, 422, 443, 461 nm for 2). The red shift phenomenon can be attributed to the π-stacking of the aromatic rings and other intermolecular Interactions in these molecules in the solid state. Especially, the strong Cu(Ⅰ)…Cu(Ⅰ) interaction of 2 can decrease the HOMO­LUMO energy gap with the red-shifted emission wavelength.

Tunable Luminescence and Application in Dye-Sensitized Solar Cells of Zn(II)/Hg(II) Complexes: Methyl Substitution-Induced Supramolecular Structures Based on (E)-N-(6-Methoxypyridin-2-ylmethylene)arylamine Derivatives.

Using Schiff-base ligands (E)-N-(6-methoxypyridin-2-yl)(CH═NAr) (where Ar = C6H5, L1; 2-MeC6H4, L2; 2,4,6-Me3C6H2, L3), six Zn(II)/Hg(II) complexes, namely, [ZnL1Cl2] (Zn1), [HgL1Cl2] (Hg1), [ZnL2Cl2] (Zn2), [HgL2Cl2] (Hg2), [ZnL3Cl2] (Zn3), and [HgL3Cl2] (Hg3) have been synthesized under solvothermal conditions. The structures of six complexes have been established by X-ray single-crystal analysis and further physically characterized by EA, FT-IR, (1)H NMR, and ESI-MS. The crystal structures of these complexes indicate that noncovalent interactions, such as hydrogen bonds, C-H···Cl, and π···π stacking, play essential roles in constructing the resulting supramolecular structures (1D for Hg3; 2D for Zn2, Hg2; 3D for Zn1, Hg1, and Zn3). Upon irradiation with UV light, the emission of complexes Zn1-Zn3 and Hg1-Hg3 could be finely tuned from green (480-540 nm) in the solid state to blue (402-425 nm) in acetonitrile solution. It showed that the ligand and metal cation can influence the structures and luminescence properties of complexes such as emission intensities and maximum wavelengths. Since these ligands and complexes could compensate for the absorption of N719 in the low-wavelength region of the visible spectrum and reduce charge recombination of the injected electron, the ligands L1-L3 and complexes Zn3/Hg3 were employed to prepare cosensitized dye-sensitized solar cells devices for investigating the influences of the electron-donating group and coordination on the DSSCs performance. Compared to DSSCs only being sensitized by N719, these prepared ligands and complexes chosen to cosensitize N719 in solar cell do enhanced its performance by 11-41%. In particular, a DSSC using L3 as cosensitizer displays better photovoltaic performance with a short circuit current density of 18.18 mA cm(-2), corresponding to a conversion efficiency of 7.25%. It is much higher than that for DSSCs only sensitized by N719 (5.14%).

[A purple-emitting luminescence complex [Cd(bpdc)(phen)2(H2O)] . 6H2O: synthesis, structure and spectral properties].

A supramolecular Cd(II) complex[Cd(bpdc) (phen)2 (H2O)] . 6H20 (1) was synthesized with 2, 4'-biphenyldicarboxylic acid (H2bpdc) and 1, 10-phenanthroline (phen) under hydrothermal conditions and characterized by single-crystal X-ray diffraction elemental analysis, and IR spectrum. Single-crystal X-ray analysis reveals complex 1 crystalizes in the triclinic P 1 space group, the metal center Cd(II) ion is six-coordinated and exhibits a distorted octahedron geometry arrangement. 3D supramolecular structure could be formed taking into account two kinds of hydrogen bonds and π--π interactions. At the same time, we discussed the luminescent properties of complex 1 in the solid-state as well as in the solvents at different temperatures. When excited at 350 nm, in the solid state at 298 K, 1 has purple luminescence with emission band at 390 nm; in the solid state at 77 K, 1 displays two emission bands at 380 and 520 nm. Because the vibration structure is more defined at low temperature, at 298 K, 1 also has purple luminescence in DMSO and CH3OH solutions with emission bands at 380 and 375 nm, which are blue-shifted compared with solid-state maximum emission band. These all can be attribute to the π*-->π transition based on the coordinate ligands. The fluorescence decay curves of complex 1 indicate that the processes of decay consist of two components. At 298 K, the lifetime of 1 is longer in DMSO solution (τ1 =1. 73 µs and τ2 =14. 07 µs) than that in CH3OH solution (τ1 =1. 21 µs and τ2 = 12. 44 µs). Moreover, the-lifetime of 1 is longer at 77 K (τ1 =1. 96 µs and τ2= 16. 11 µs) than that at 298 K in the solid state (τ1= 1. 20 µs and τ2 =11. 34 µs). The results might be caused by the increase in radiative rate and decrease in non-radiative rate at low temperature.

[Synthesis, crystal structure and spectral properties study of a 3D netlike coordination polymer [Zn(HBIDC) x H2O]n].

The 3D netlike coordination polymer of Zn II with benzimidazole-5,6-dicarboxylic acid (H3BIDC), [Zn(HBIDC) x H2O]n was synthesized by the hydrothermal method through self-assembling. The crystal structure of complex 1 was characterized by single-crystal X-ray diffraction, elemental analysis and IR spectra, and we also studied the fluorescence properties of complex 1 in DMSO and in the solid state with UV-Vis absorption spectra, fluorescence spectra and fluorescence lifetime. Complex 1 has blue luminescence in solutions of DMSO with emission band at 481 nm; and has blue luminescence in the solid state at room temperature with a strong emission band at 493 nm, and these all can be attributed to the pi* --> pi transition based on the benzimidazole-5,6-dicarboxy acid. The experimental results indicate that complex 1 displays higher fluorescence quantum efficiency and can be used as a potential blue luminescence material.

(E)-2,4,6-Trimethyl-N-(pyridin-2-yl-methyl-idene)aniline.

In the title compound, C(15)H(16)N(2), has an E conformation about the central N=C bond. The benzene and pyridine rings are almost normal to one another with a dihedral angle of 87.47(8)°. In the crystal, there are no classical hydrogen bonds.

N,N'-Bis[1-(pyridin-2-yl)-ethyl-idene]benzene-1,4-diamine.

In the title compound, C(20)H(18)N(4), the benzene ring lies about an inversion center. The central benzene-1,4-diamine unit is connected to two pyridine rings by the C=N imine bonds. The dihedral angle between the benzene and pyridine rings is 82.9 (1)°.

[Synthesis, characterization and luminescence properties of a copper (I) complex].

Binuclear complex [Cu2 (mu-I)2 (phen)2] x CH3CN(1)(phen = 1,10-phenanthroline) was synthesized under solvothermal conditions and characterized by elemental analysis, IR spectrum, and single-crystal X-ray diffraction. X-ray diffraction analysis reveals that complex 1 is monoclinic, space group P2(1/n), and the cell parameters are: alpha = 10.505 A, b = 23.628 A, c = 10. 676 A, alpha = 90, beta = 91.40 degrees and gamma = 90 degrees. The authors have studied the luminescence property of 1, Complex 1 has blue-purple luminescence in solutions of DMSO with emission bands at 369, 380 and 460sh nm; and has red luminescence in the solid state at room temperature with a broad emission band at 650-678 nm. These all can be attributed to the pi* --> pi transition based on the ligand. In the solid state, the emission frequencies for complex 1 are red-shifted about 280 nm compared with their emission maximum peaks in solutions of DMSO. This red-shift of emission energy from solution to solid is likely to be caused by the intermolecular pi--pi packing interaction in the solid state which effectively decreases the energy gap. The fluorescence decay curve of complex 1 indicated that the processes of decay consists of two components, whose corresponding lifetimes are tau1 = 1.36 micros and tau2 = 5.98 micros, corresponding factors are 50.21% and 49.79% in DMSO solutions, and tau1 = 1.42 micros, tau2 = 8.85 micros, corresponding factors are 51.15% and 48.85% in the solid state.

[Synthesis, crystal structure and luminescent properties of a dysprosium coordinaation polymer based on pyridine-2, 6-dicarboxylic acid].

2-D layered Dy coordination polymer [Dy(PDA) (HPDA)I]n (1)(H2PDA = pyridine-2,6-dicarboxylic acid) with (4.8(2)) topological network was synthesized under hydrothermal conditions and was characterized by elemental analysis, IR spectrum, and single-crystal X-ray diffraction. X-ray diffraction analysis reveals that compound 1 is monoclinic, space group P2(1)/c. In the structure of compound 1, metal-centered Dy is connected via O atoms of H2PDA ligands to form a (4.82) topology network. The 3-D supramolecular structure of 1 is constructed through pi--pi stacking interactions between the adjacent layers. The luminescence properties of 1 were determined by UV-Vis and fluorescence spectrum in solid state at room temperature. The H2PDA and 1 exhibit the similar broad maximum absorption peak at 280 nm, which are attributed to ligand-centered pi--pi* transition. The fluorescence emission band based on ligand-center and characteristic emission of Dy3+ at the same maximum excitation wavelength of 280 nm were observed in 1. The fluorescence decay curve of complex 1 indicated that the processes of decay consists of two components, of which corresponding lifetimes tau1 = 3.61 micros and tau2 = 12.81 micros.

[Hydrothermal synthesis, crystal structure and luminescence property of 3D supermolecular compound [Zn(H2O)6].(C16H8O8)].

A supermolecular compound [Zn(H2O)6].(C16H8O8) was synthesized with 3,3', 4,4'-bipthenyltetracarboxylic acid (H4BPTC) and Zn(CH3COO)2.2H2O. Its structure was determined by single crystal X-ray diffraction, IR and element analysis. The crystal belongs to triclinic system with space group and the cell parameters are: a = 0.65484 (13) nm, b = 0.79388 (16) nm, c = 0.96812 (19) nm, alpha = 76.29 (3) degrees, beta = 87.75 (3) degrees, gamma = 86.43 (3) degrees, Z=1, R1 = 0.0665, wR2 = 0.1833, and GOF = 1.021. We have studied the luminescence property of compound 1, The compound 1 has blue-purple luminescence in solutions of DMSO and green luminescence in the solid state at room temperature. In the solid state, the emission frequencies for complex 1 are red-shifted compared with their emission maximum peaks in solutions of DMSO. This red-shift of emission energy from solution to solid is likely to be caused by the intermolecular interaction in the solid state that effectively decreases the energy gap.

Tetra-µ-acetato-κO:O';κO,O':O;κO:O,O'-bis-[(acetato-κO,O')(1,10-phenanthroline-κN,N')europium(III)].

In the title centrosymmetric dinuclear complex, [Eu(2)(CH(3)CO(2))(6)(C(12)H(8)N(2))(2)], the Eu(III) atom is nine-coordinated by two N atoms from a 1,10-phenanthroline ligand and seven O atoms from five acetate ligands (two bidentate, three monodentate). The crystal structure is stabilized by π-π stacking inter-actions between the pyridine and benzene rings of adjacent mol-ecules, with a centroid-centroid distance of 3.829 (2) Å.

A self-calibrating dual responsive platform for the sensitive detection of sulfite and sulfonic derivatives based on a robust Hf(iv) metal-organic framework.

A robust hafnium-based metal organic framework, Hf-PBTA, with sensitive and self-calibrating dual-emissive fluorescence response towards sulfite and sulfonic derivatives, including antibiotic sulfamethazine, has been developed, which shows fast detection of sulfite ions at a concentration as low as 76 ppb. The opposite response tendency from two radiative pathways towards aromatic sulfonic molecules and sulfite anions stems from the synergistic effect of the pyridine protonation effect, π-π stacking interaction and intramolecular twist motion.

2,6-Bis[1-(2-methyl-phenyl-imino)eth-yl]pyridine.

The mol-ecule of the title compound, C(23)H(23)N(3), which was synthesized by the condensation reaction between 2,6-diacetyl-pyridine and 2-dimethyl-aniline, adopts an E configuration about both C=N imine bonds. The dihedral angles formed by the benzene rings with the pyridine ring are 89.68 (5) and 53.62 (6)°.

2,6-Bis[1-(2,6-diethyl-phenyl-imino)eth-yl]pyridine.

The title compound, C(29)H(35)N(3), is the product of the condensation reaction between 2,6-diacetyl-pyridine and 2,6-diethyl-aniline. In the mol-ecule, the pyridyl ring is coplanar with the imino functional groups [torsion angles in the range 177.1 (2)-179.9 (2)°. The two 2,6-diethyl-substituted benzene rings are approximately perpendicular to the ethyl-idenepyridine central core, the dihedral angles being 88.7 (1) and 88.4 (1)°, respectively.

1,1'-Dimethyl-1,1'-(butane-1,4-di-yl)dipyrrolidinium dibromide methanol disolvate.

In the title compound, C(14)H(30)N(2) (2+)·2Br(-)·2CH(3)OH, two terminal C atoms of the butane chain are connected to two N atoms of the 1-methyl-pyrollidines, forming a linear diquaternary ammonium cation. The cation lies across a centre of inversion located between the two central C atoms of the butane chain. The asymmetric unit therefore comprises one half-cation, a bromide anion and a methanol solvent mol-ecule. In the crystal structure, the bromide anions are linked to the methanol solvent mol-ecules by O-H⋯Br hydrogen bonds.

Different conjugated system Zn(ii) Schiff base complexes: supramolecular structure, luminescent properties, and applications in the PMMA-doped hybrid materials.

A series of Zn(ii) complexes with different conjugated systems, [ZnL1Cl2]2 (Zn1), [ZnL2Cl2] (Zn2), [Zn(L3)2]·(ClO4)2 (Zn3), [Zn2L4Cl4] (Zn4), and [ZnL5Cl2] (Zn5), were synthesized and subsequently characterized via single crystal X-ray diffraction, 1H and 13C NMR, FT-IR, elemental analyses, melting point, and PXRD. The X-ray diffraction analyses revealed that the supramolecular frameworks of complexes Zn1-Zn5 are constructed by C-HO/Cl hydrogen bonds and ππ interactions. Complexes Zn1-Zn3 feature 3D 6-connected {412·63} topological structures, whereas complex Zn4 exhibits a 3D 7-connected supramolecular framework with a {417·64} topological structure. However, complex Zn5 shows one-dimensional "wave-like" chains. Based on these varied structures, the emission maximum wavelengths of complexes Zn1-Zn5 can be tuned in a wide range of 461-592 nm due to the red shift direction of λem caused by different conjugated systems and their electron donating abilities. Complex Zn3 shows a strong luminescence in the solid state and in the acetonitrile solution. Therefore, a series of Zn3-poly(methylmethacrylate) (Zn3-PMMA) hybrid materials were obtained by controlling the concentration of complex Zn3 in poly(methylmethacrylate) (PMMA). At an optimal concentration of 4%, the doped polymer film of Zn3-PMMA displays strong green luminescence emissions that are 19-fold in the luminescence intensities and 98 °C higher in the thermal stability temperature compared to the Zn3 film.

Facile luminescent tuning of Zn(II)/Hg(II) complexes based on flexible, semi-rigid and rigid polydentate Schiff bases from blue to green to red: structural, photophysics, electrochemistry and theoretical calculations studies.

The photophysical properties of Zn(II)/Hg(II) Schiff base complexes could be fine and predictably tuned over a wide range of wavelengths by changing the ligand structures. A new series of polydentate Schiff base-type ligands, N,N'-bis(2-pyridinylethylidene)R(3)-1,2-diamine (), which contain a flexible, semi-rigid or rigid group (R(3) = butyl, cyclohexane, tolyl and phenylene), has been designed and employed for synthetizing new mononuclear or binuclear trans Zn(II)/Hg(II) complexes with a general formula of [M()Cl2] ( = N,N'-bis(2-pyridinylethylidene)phenylene-1,2-diamine, M = Zn, ; M = Hg, ), [M()Cl2] ( = N,N'-bis(2-pyridinylethylidene)toluene-3,4-diamine, M = Zn, ; M = Hg, ), [M2()Cl4]·nCH2Cl2 ( = N,N'-bis(2-pyridinylmethylene)cyclohexane-1,2-diamine, M = Zn, n = 0, ; M = Hg, n = 1, ), [M2()Cl4]·nCH3OH ( = N,N'-bis(2-pyridinylethylidene)cyclohexane-1,2-diamine, M = Zn, n = 1, ; M = Hg, n = 0, ), [M2()Cl4] ( = N,N'-bis(3-methoxy-2-pyridinylmethylene)-cyclohexane-1,2-diamine, M = Zn, ; M = Hg, ), [M2()Cl4]·nCH3CN ( = N,N'-bis(3-methoxy-2-pyridinylmethylene)butane-1,4-diamine, M = Zn, n = 4, ; M = Hg, n = 0, ). All the ligands and complexes have been characterized by elemental analyses, IR spectra, and (1)H NMR spectra. Twelve structures of , , , , , and crystallized in three different conditions are further determined by single-crystal X-ray diffraction analyses. Their properties are fully characterized by UV-vis and fluorescence spectra both in solution and the solid state at room temperature. The luminescence color of these Zn(II)/Hg(II) Schiff base complexes could be tuned from blue to green to red (429-639 nm for , 434-627 nm for ) in solution by changing the ligand conjugated systems from flexibile () to semi-rigid () to rigid (). The spectra of the free Schiff bases are centered around 402-571 nm, which are perturbed upon the coordination to the Zn(II)/Hg(II) ion. Both the electrochemical data and TD-DFT calculations show that the HOMO-LUMO band gap from the ligand to the complex is reduced by complexation. Meanwhile, the emission efficiencies of Zn(II)-complexes are found to be strongly dependent on the Schiff-base ligands with quantum yields ranging from 14% to 25% for . However, the emission efficiencies dramatically decline in Hg(II)-complexes with quantum yields ranging from 4% to 19%, due to the heavy atom effect.

Solvatochromic and application in dye-sensitized solar cells of sandwich-like Cd(II) complexes: supramolecular architectures based on N(1),N(3)-bis[(6-methoxypyridin-2-yl)methylene]benzene-1,3-diamine.

A novel polydentate Schiff base ligand N(1),N(3)-bis[(6-methoxypyridin-2-yl)methylene]benzene-1,3-diamine (L) and its two dinuclear sandwich-like complexes {[CdL(NO3)(H2O)]·NO3}2 (1) and {[CdL(CH3CN)(H2O)]·(ClO4)2·(CH3CN)2}2 (2) were synthesized. Both C-H∙∙∙O, C-H∙∙∙N and π-π non-covalent interactions had essential roles in constructing the resulting three-dimensional supramolecular networks. L emits a more intense blue-green fluorescence emission around 493 nm than in dilute solution, exhibiting stacking-induced emission properties. Complexes 1 and 2 exhibited the dual properties of exceptional solvatochromism and fluorescence quenching towards CH3OH molecules. As these compounds could overcome the absent absorption of ruthenium complex N719 in the low wavelength region of the visible spectrum, offset the competitive visible light absorption of I3(-) and reduce the charge recombination of injected electrons, the Schiff base ligand l and complexes 1 and 2 were used as co-sensitizers in combination with N719 to investigate their effect on enhancing the performance of dye-sensitized solar cells. A short circuit current density of 14.37 mA cm(-2), an open-circuit voltage of 0.71 V and a fill factor of 0.61 corresponding to an overall conversion efficiency of 6.17% under AM 1.5 G solar irradiation were achieved when 1 was used as a co-sensitizer, which are much higher than the results obtained for dye-sensitized solar cells sensitized by N719 alone (5.06%).