Fluorescent Emission In Solid State Research Articles

Synthesis, characterisation and catalytic activity of 4, 5-imidazoledicarboxylate ligated Co(II) and Cd(II) metal-organic coordination complexes

Two mono nuclear coordination complexes, namely, [Co(4,5-Imdc)2 (H2O)2] (1) and [Cd(4,5-Imdc)2(H2O)3]·H2O (2) were constructed using Co(II) and Cd(II) metal salts with 4,5-Imidazoledicarboxylic acid (4,5-Imdc) as organic ligand. Both 1, 2 were structurally characterized by single crystal XRD and the results reveal that 1 belongs to P21/n space group with unit cell parameters [a = 5.0514(3) Å, b = 22.5786(9) Å, c = 6.5377(3) Å, β = 111.5°] whereas, 2 belongs to P21/c space group with unit cell parameters [a = 6.9116(1) Å, b = 17.4579(2) Å, c = 13.8941(2) Å, β = 97.7°]. While Co(II) in 1 exhibited a six coordination geometry with 4,5-Imdc and water molecules, Cd(II) ion in 2 showed a seven coordination with the same ligand and solvent. In both 1 and 2, the hydrogen bond interactions with mononuclear unit generated 3D-supramolecular structures. Both complexes exhibit solid state fluorescent emission at room temperature. The efficacy of both the complexes as heterogeneous catalysts was examined in the green synthesis of six pyrano[2,3,c]pyrazole derivatives with ethanol as solvent via one-pot reaction between four components, a mixture of aromatic aldehyde, malononitrile, hydrazine hydrate and dimethyl acetylenedicarboxylate. Both 1 and 2 have produced pyrano [2,3,c]pyrazoles in impressive yields (92–98%) at room temperature in short interval of times (<20 min), with no need for any chromatographic separations. With good stability, ease of preparation and recovery plus reusability up to six cycles, both 1 and 2 prove to be excellent environmental friendly catalysts for the value-added organic transformations using green principles.

Dendritic copper phthalocyanine with aggregation induced blue emission and solid-state fluorescence

In this work, dendritic copper phthalocyanine (CuPc) showing obvious aggregation induced emission (AIE) and strong solid-state fluorescence was synthesized. It was found that synthesized CuPc can be easily solubilized in polar aprotic solvent, where no fluorescence signal was detected. Interestingly, both the CuPc aggregates in solution and solid-state powder exhibited strong fluorescence emission around 480nm, which should be attributed to the restriction of intramolecular rotation as rationalized in aggregation induced emission framework. Meanwhile the obvious crystalline enhanced solid-state fluorescent emission is observed for CuPc powder.

Synthesis and aggregation-induced emission enhancement of naphthalimide-rhodamine dye

Abstract A series of naphthalimide-rhodamine dye L1–4 with the different terminal structures were designed and synthesized. The rhodamine was used as bulky rigid substituent of naphthalimide to enhance the AIE property. All the naphthalimide-rhodamine dye exhibited the significant aggregation-induced emission enhancement. The strong fluorescence emissions in solid state were observed with emission peaks ranging from 549 to 608 nm. In high fW mixture solution, the fluorescence intensity enhanced with the increase of water content, which can be attributed to two types of aggregation-induced morphology. The AIE dye-doped silica nanoparticles (Si-NPs) were prepared and exhibited good solubility in pure water. In addition, dye L1 and L2 exhibited the selective recognition toward Hg2+ ions and were successfully applied to the bioimages in living cells. The intramolecular fluorescence resonance energy transfer mechanism from the naphthalimide moiety to the rhodamine moiety was investigated.

Structures and photoluminescence of coordination polymers assembled from bifunctional ligand containing both tetrazole and imidazole groups

Three new coordination polymers, namely, {[Cu2(IPT)(SO4)(OH)(H2O)]·H2O}n (HIPT=5-(4-(1H-imidazol-1-yl)phenyl)- 1H-tetrazolate, 1), {[Cd2(IPT)(NPA)(OH)]·H2O}n (H2NPA=5-nitroisophthalic acid, 2), and {[Zn2(IPT)(IDC)(H2O)]·3H2O}n (H3IDC=1H-imidazole-4,5-dicarboxylic acid, 3), were assembled from a bifunctional organic ligand containing both tetrazole and imidazole groups with/without the aid of carboxylate coligands. Compound 1 possesses 2D structure built by 1D [Cu2(IPT)(SO4)(OH)]n secondary building blocks and IPT− linkers. The 2D networks are linked into 3D supramolecular framework via water chains in helical conformation. Compound 2 displays 3D pillar-layer framework with 2D layers based on tetranuclear Cd(II) SBUs and NPA2− pillars. Compound 3 exhibits a 3D framework constructed from the interconnection of 1D [Zn-IDC]n chains and binuclear Zn2(IPT)2 rings. The thermal stabilities of porous compound 3 and luminescent properties of compounds 2 and 3 have also been studied in detail. They exhibit intense solid-state fluorescent emissions at room temperature.

Feasibility of highly branched cyclic dextrin as an excipient matrix in dry powder inhalers

We investigated the feasibility of highly branched cyclic dextrin (HBCD) as an excipient matrix in dry powder inhalers (DPIs). The fine particles of HBCD and HBCD/active pharmaceutical ingredients (APIs) were prepared by spray-drying an ethanol-aqueous solution containing HBCD. The particle size of spray-dried HBCD itself was approximately 3.0μm with a wrinkled shape. Solid-state fluorescence emission spectroscopy of 1-naphthoic acid (1-NPA) showed that it was dispersed in a molecular dispersion/solid solution, if the model compound of 1-NPA was spray-dried with HBCD. Powder X-ray diffraction and differential scanning calorimetry indicate that 1-NPA was in the amorphous state after spray-drying with HBCD, which is confirmed by the fluorescence measurements, 1-NPA could be incorporated into HBCD. When the antimycobacterial agent, rifampicin, was spray-dried with HBCD for the purpose of pulmonary administration, the emitted dose and fine-particle fraction of the spray-dried particles of rifampicin with HBCD were 95.7±1.7% and 39.5±5.7%, respectively. The results indicated that HBCD possessed a high potential as an excipient in DPIs, not only by molecular association of API molecules with HBCD, but also by that of API fine crystals.

Structural modulation and properties of silver(I) coordination polymers from 2,6-naphthalenedicarboxylic acid and flexible N-donor linkers

Based on the N-donor auxiliary ligand effect, four new silver(I) coordination polymers derived from 2,6-naphthalenedicarboxylic acid (H2ndc), namely [Ag(L1)(ndc)0.5] n (1), [Ag(L2)(ndc)0.5] n (2), {[Ag(L3)(ndc)0.5]·0.5(H2ndc)} n (3), and [Ag(L4)(H2O)·Hndc] n (4) (L1 = 1,3-bis(thiabendazole)butane, L2 = 4,4′-bis(pyrazole-1-ylmethyl)-biphenyl, L3 = 1,4-bis(benzimidazole)butane, L4 = 4,4′-dipyridylamine), have been synthesized by solvothermal reactions. Complex 1 possesses a 1D infinite loop and chain, which is further extended into a 3D supramolecular framework by π–π stacking interactions. Complex 2 presents an unprecedented 3D (3,4)-connected lim (baa-e-3,4-Imma) topology with the Schlafli symbol of (4.102)2(42.104). Complex 3 exhibits a 2D three-connected hcb (Shubnikov hexagonal plane) network and the Schlafli symbol is (63). Complex 4 shows a 1D linear chain, which generates a 2D supramolecular layer via hydrogen bonding interactions. Solid-state properties of 1–4 have also been investigated, which display high thermal stability and intense fluorescent emission in solid state. Moreover, the complexes manifest excellent catalytic activities for the decomposition of Congo red azo dye by hydrogen peroxide in a Fenton-like process.

Tunable solid-state fluorescent materials for supramolecular encryption.

Tunable solid-state fluorescent materials are ideal for applications in security printing technologies. A document possesses a high level of security if its encrypted information can be authenticated without being decoded, while also being resistant to counterfeiting. Herein, we describe a heterorotaxane with tunable solid-state fluorescent emissions enabled through reversible manipulation of its aggregation by supramolecular encapsulation. The dynamic nature of this fluorescent material is based on a complex set of equilibria, whose fluorescence output depends non-linearly on the chemical inputs and the composition of the paper. By applying this system in fluorescent security inks, the information encoded in polychromic images can be protected in such a way that it is close to impossible to reverse engineer, as well as being easy to verify. This system constitutes a unique application of responsive complex equilibria in the form of a cryptographic algorithm that protects valuable information printed using tunable solid-state fluorescent materials.

Syntheses, structures, and luminescence of two Zn(II) coordination polymers based on 5-(4-imidazol-1-yl-phenyl)-2H-tetrazole and carboxylates

Reactions of Zn(II) salts, 5-(4-(1H-imidazol-1-yl)phenyl)-1H-tetrazolate (HIPT) and 2-mercaptobenzoic acid or 2-propyl-1H-imidazole-4,5-dicarboxylic acid (H3PrIDC), result in two mixed-ligand coordination polymers (CPs), [Zn2(IPT)(DSDB)(OH)]n (H2DSDB = 2,2′-disulfanediyldibenzoic acid, 1) and [Zn2(IPT)(PrIDC)(H2O)]n (H3PrIDC = 2-propyl-1H-imidazole-4,5-dicarboxylic acid, 2). Compound 1 possesses a 2-D structure built by 1-D [Zn(IPT)]n chains and DSDB2− connectors, in which the DSDB2− is generated via in situ reaction from 2-mercaptobenzoic acid. It displays a new intricate 4-nodal {3·4·6·7·8·9}{3·6·7·8·9·10}{3·8·9}{4·6·8} topology. Compound 2 displays a 3-D framework with new 3-connected topology with Schläfli symbol of (4·8·10) (8·122), in which the 1-D Zn-carboxylate chains were bridged by 3-connected IPT− ligands. The thermal stabilities and luminescence properties of 1 and 2 have also been studied. The compounds exhibit intense solid-state fluorescent emissions at room temperature.

Three Silver(I) Coordination Polymers Constructed from Flexible Bis(benzimidazole) and Carboxylates Ligands

AbstractUnder hydrothermal conditions, three new AgI coordination polymers, [Ag(L1)(Hmip)]n (1), [Ag(L2)0.5(ndc)0.5]n (2), and {[Ag(L3)0.5(Htbi)]·0.25H2O}n (3) [H2mip = 5‐methylisophthalic acid, L1 = 1,4‐bis(2‐methylbenzimidazol‐1‐ylmethyl)benzene, H2ndc = 2,6‐naphthalenedicarboxylic acid, L2 = 1,3‐bis(2‐methylbenzimidazol‐1‐ylmethyl)benzene, H2tbi = 5‐tert‐butyl isophthalic acid, L3 = 1,4‐bis(5,6‐dimethylbenzimidazole)butane] were synthesized by employing flexible bis(benzimidazole) and dicarboxylic acid ligands. Polymer 1 displays a 2D 4‐connected 4L2 underlying net topology with the point symbol of (65.8) in standard representation. Compound 2 possesses a 2D uninodal 4‐connected Shubnikov tetragonal plane net (sql) based on a dinuclear AgI clusters with the point symbol (44.62), which is further extended into a 3D supramolecular framework by π–π interactions. Compound 3 possesses dinuclear molecular complex groups, which form chains by weak Ag–O (2.6 Å) coordination bonds, and further assembled into a 2D supramolecular layer by hydrogen bonds and π–π stacking interactions. These complexes exhibit intense fluorescent emissions in solid state. UV/Vis diffuse reflection spectra and the excellent catalytic activity for the degradation of the congo red azo dye in a Fenton‐like process are discussed.

Detection of ethanol in alcoholic beverages or vapor phase using fluorescent molecules embedded in a nanofibrous polymer.

An alcohol sensor was developed using the solid-state fluorescence emission of terphenyl-ol (TPhOH) derivatives. Admixtures of TPhOH and sodium carbonate exhibited bright sky-blue fluorescence in the solid state upon addition of small quantities of ethanol. A series of terphenol derivatives was synthesized, and the effects of solvent polarities and the structures of these π-conjugated systems on their fluorescence were systematically investigated by using fluorescence spectroscopy. In particular, π-extended TPhOHs and TPhOHs containing electron-withdrawing groups exhibited significant solvatochromism, and fluorescence colors varied from blue to red. Detection of ethanol contents in alcohol beverages (detection limit ∼ 5 v/v %) was demonstrated using different TPhOHs revealing the effect of molecular structure on sensing properties. Ethanol contents in alcoholic beverages could be estimated from the intensity of the fluorescence elicited from the TPhOHs. Moreover, when terphenol and Na2CO3 were combined with a water-absorbent polymer, ethanol could be detected at lower concentrations. Detection of ethanol vapor (8 v/v % in air) was also accomplished using a nanofibrous polymer scaffold as the immobilized sensing film.

Strategy to enhance solid-state fluorescence and aggregation-induced emission enhancement effect in pyrimidine boron complexes.

The synthesis and the solution/solid-state fluorescence properties of pyrimidine-based monoboron complexes differing in terms of the substituents [either two fluorine atoms (BF2 complex) or two phenyl groups (BPh2 complex)] on the boron atom are reported herein. Unrestricted C-Ar intramolecular rotation in the non-, trifluoromethyl-, and cyano-substituted derivatives resulted in negligible fluorescence in solution. On the other hand, methoxy- and dimethylamino-substituted analogues caused the restriction of the C-Ar intramolecular rotation and consequently resulted in relatively strong fluorescence in solution. The non-, trifluoromethyl-, and cyano-substituted derivatives showed a pronounced aggregation-induced emission enhancement effect. Dimethylamino-substituted derivatives exhibited solvatochromism in the fluorescence spectra. Substitution with BPh2 effectively enhanced the fluorescence quantum yield compared to the corresponding BF2 complexes in the solid-state.

Assembly of Cd(ii) coordination polymers: structural variation, supramolecular isomers, and temperature/anion-induced solvent-mediated structural transformations

The reactions of Cd(II) salts and 5-(3-(1H-imidazol-1-yl)phenyl)-1H-tetrazolate (3-HIPT) resulted in eight new coordination polymers (CPs), namely, {[Cd(3-IPT)2(H2O)2]·H2O}n (1 and 2), {[Cd(3-IPT)2(H2O)2]·2H2O}n (3), [Cd(3-IPT)(H2O)Cl]n (4), [Cd(3-IPT)Cl]n (5), [Cd(3-HIPT)I2]n (6), [Cd(3-IPT)I]n (7), and [Cd(3-HIPT)2]n (8). Single-crystal X-ray analysis revealed that compound 1 is a 1D beaded chain, whereas compounds 2 and 3 are made of 2D networks. Compounds 1–3 are supramolecular isomers; their synthesis can be controlled under different temperatures and concentrations. The results showed that compounds 1 and 3 are the most thermodynamically and kinetically favored products, respectively. The thermodynamic stability of compound 1 may be attributed to the formation of the smallest M2L2 ring in the compound. Compounds 4–7 were obtained at higher Cl−/I− concentrations. Compound 4 is a 2D net composed of 1D [Cd(3-IPT)]n chains and μ2-Cl and μ2-H2O connectors. Compound 5 is a (3,6)-connected 3D framework with rtl topology. Compound 6 possesses a 1D chain with 3-HIPT ligands on both sides. Compound 7 is a 2D (4·82) net. Compound 8, a 3D pcu framework based on trinuclear linear SBUs, was formed when Cd(CF3CO2)2 was introduced at 170 °C. Based on a temperature-changing cycle, compounds 1 and 3 display crystal-to-amorphous-to-crystal phase transitions accompanying the dehydration–rehydration process, whereas compound 2 only displays crystal-to-amorphous phase transition when the temperature is increased and cannot go back to the crystal phase again. Interestingly, solvent-mediated structural transformations were accomplished among the selected compounds. When compounds 2, 3, 6, 7, or 8 were left in a water and NaCl solution at 170 °C, they were partly/fully transformed into compounds 1 and 5, respectively. When compound 5 was recrystallized in water at 120 and 170 °C, it was partly and fully transformed into compounds 2 and 1, respectively. Such transformations were induced by the temperature or an anion. In addition, the thermal stabilities and luminescence properties of selected compounds have also been studied in detail. The complexes exhibit intense solid-state fluorescence emission at room temperature.

How Structure-Directing Cations Tune the Fluorescence of Metal–Organic Frameworks

A series of metal-organic frameworks (MOFs), {Zn-BTC}{cations}, which contain anionic Zn-BTC coordination polymers, is reported here. It was observed that cations with different hydrogen-bond forming abilities could significantly affect the coordination of Zn-BTC structures in the frameworks. The 13 Zn-BTC MOFs reported herein showed solid-state fluorescent emission in the visible spectrum, and the fluorescence of the frameworks was tunable by adjusting the interactions of the cations with the anionic Zn-BTC structure in the MOFs.

Anion-directed assembly and crystal transformation of Ag(I) coordination polymers with a versatile tripyridyltriazole ligand 3,4-bis(2-pyridyl)-5-(4-pyridyl)-1,2,4-triazole

A series of distinct Ag(I) coordination polymers, namely {[Ag2(L224)(H2O)3](SiF6)(H2O)4}n (1), {[Ag2(L224)2(NO3)](NO3)(H2O)}n (3), {[Ag2(L224)(OOCC6H5)(H2O)](NO3)(H2O)2}n (4), and {[Ag(L224)2](CF3SO3)(H2O)0.25}n (5) have been synthesized by assembling a versatile ligand 3,4-bis(2-pyridyl)-5-(4-pyridyl)-1,2,4-triazole (L224) with different Ag(I) salts. Their diverse 1D and 2D coordination arrays indicate the critical role of counterions in structural assemblies. Interestingly, single-crystal-to-single-crystal (SC–SC) transformation from 1 to {[Ag2(L224)(CF3COO)2(H2O)](H2O)}n (2) will occur in the water solution of Ag(CF3COO). Structural comparison and mechanism of SC–SC transformation are discussed. These Ag(I) coordination polymers show enhanced ligand-based solid-state fluorescent emissions.

Synthesis, characterization and luminescence of Cd(II), Zn(II) complexes with 1,2,3-triazole derivatives and in situ solvothermal decarboxylation of the ligands

The complexes [CdCl(mptc)(H2O)2]n (1), Zn(mptc)(Hmptc)Br (2), {[Zn(mptc)3]2[Zn(H2O)6]·4H2O} (3) and Zn(mpt)2Cl2 (4) (mpt=5-methyl-1-phenyl-1H-1,2,3-triazole) were prepared by 5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid (Hmptc) and Cd2+, Zn2+ respectively in different conditions. We found an interesting phenomenon of in situ decarboxylic reaction in complex 4. The same discovery was also in Zn(ipmt)2Br2 (5) (ipmt=1-(4-iodophenyl)-5-methyl-1H-1,2,3-triazole), which was obtained by the reaction of 1-(4-iodophenyl)-5-methyl-1H-1,2,3-triazole-4-carboxylic acid (Hipmtc) with Zn2+ under solvothermal condition. And the crystal structures of 1–5 were determined via single-crystal X-ray diffraction. The complexes were characterized by FT-IR, elemental analyses, and solid-state fluorescent emission spectroscopy. Then, the possible mechanism of in situ solvothermal decarboxylation was discussed.

Syntheses, Structures, and Characterization of Two Novel Copper(II) and Cadmium(II) Compounds Based on Pyridyl Conjugated 1,2,3-Triazole

Two new complexes with 5-methyl-1-(pyridine-3-yl)-1H-1,2,3-triazole-4-carboxylic acid (Hmptc) ligand: [Cd(mptc)2(H2O)4] (1) and [Cu(mptc)4·2H2O]n (2) were prepared and their crystal structures were determined by single crystal X-ray diffraction analyses. In complex 1, the Cd(II) ions coordinates with the pyridyl nitogen atom from the Hmptc ligand, forming a mononuclear Cd(II) compound. Complex 2 exhibits a novel twodimensional (2D) polymer in which four Hmptc ligands stabilize the Cu(II) atom. And the coordination involves one nitrogen atom of the triazole, one oxygen atom of the carboxylic acid and the pyridyl nitrogen atom. In addition, FT-IR and solid-state fluorescent emission spectroscopy of two compounds have been determined.

Synthesis, crystal structures and photophysical properties of novel boron-containing derivatives of phenalene with bright solid-state luminescence

A novel series of boron-containing derivatives of phenalene have been synthesized. These compounds with emission changes from green, yellow to red were obtained by introducing electron-donating or electron-withdrawing substituent groups. Electron density distribution and energy levels of new compounds were calculated by density functional theory. The results show that the HOMO orbitals are delocalized over the whole molecule of the π-conjugated framework, with the LUMO orbitals mainly delocalized over the phenalene plane. The single-crystal structure demonstrates that the bulky substituents prevent the fluorophores forming short intermolecular interactions, which helps to avoid energy loss via non-irradiative decay and benefits enhancing the solid-state fluorescence emission of the compounds. Moreover, keeping intramolecular push–pull electronic structure was found to be also in favor of strengthening the fluorescent intensity of this kind of compounds.

Syntheses, Characterization, and Structures of Polynuclear Tartrato and Malato Complexes of Bivalent Manganese

Polymeric [Mn2(C4H4O6)2(H2O)].nH2O(n=2.71), [Mn(C4H4 O5)(H2O)2].H2O have been synthesized by reacting freshly prepared MnO(OH), 40%HF and corresponding α-hydroxycarboxylic acid from aqueous medium. Compounds were characterized on the basis of elemental analyses, spectroscopic, and X-ray diffraction studies. [Mn2(C4H4O6)2(H2O)].nH2O(n=2.71) crystallizes in space group P21 and three-dimensional structure consist of corrugated sheets of [Mn2{(R,R)-C4H4O6}2(H2O)] and water molecules. [Mn(C4H4O5)(H2O)2]. H2O crystallizes in space group Pbca and polymeric structure is formed of infinite number of dimeric units of Mn2[(C4H4O5)(H2O)2]2.2H2O. Hydrogen bonding interaction is operative in the crystal lattice of the compounds. Room temperature magnetic moments for tartrato and malato complexes are 5.12 and 5.47 BM respectively. Complexes exhibit fluorescence emission in solid state.

Cruciform 9,10-distyryl-2,6-bis(p-dialkylamino-styryl)anthracene homologues exhibiting alkyl length-tunable piezochromic luminescence and heat-recovery temperature of ground states

A series of 2,6-bis(p-dialkylaminostyryl)-9,10-distyrylanthracene (FCn) cruciforms with N-alkyl chains of different lengths have been synthesized, and their aggregation-enhanced fluorescence and piezochromic luminescence (PFC) behaviours are investigated. These 9,10-distyrylanthracene-containing cruciforms exhibit relatively low fluorescence quantum yields (Φ) in THF solution (Φ ≈ 10%) and moderate aggregation-enhanced emission in aqueous media (Φ ≈ 25%), but strong and chain length-dependent solid-state fluorescence emission. Grinding and pressing experiments indicate that they are all effective PFC materials in terms of mechanical stress-induced spectral shifts (ΔλPFC = 23–54 nm), moreover, the longer alkyl-containing FCn shows a larger ΔλPFC. Powder X-ray diffraction and differential scanning calorimetry measurements reveal that the transformation between the crystalline and amorphous states upon external stimuli is responsible for the reversible PFC behaviour. It is found that increasing the N-alkyl length could effectively decrease the cold-crystallization temperature of the ground states to render the PFC states with a tunable heat-recovering temperature, and ground FC10 and FC12 solids can recover spontaneously to their original states at room temperature.

Two 3D open coordination frameworks constructed by CdII or ZnII perchlorate and 4-(4-pyridyl)-3,5-bis(2-pyridyl)-1,2,4-triazole showing selective anion-exchange behaviors to acetate

Abstract Two isostructural 3D coordination polymers (CPs) {[M(L 242 ) 2 ](ClO 4 ) 2 } n (MII = CdII for 1 and Zn II for 2 ) have been constructed from metal perchlorates and a tripyridyltriazole ligand 4-(4-pyridyl)-3,5-bis(2-pyridyl)-1,2,4-triazole (L 242 ). The host framework of each CP comprises two interpenetrating lvt topological networks. Three types of 1D channels with different chirality (achirality and left-handed or right-handed helicity) are observed to hold the perchlorate guest anions. Interestingly, both CPs materials have the exclusive and irreversible anion-exchange behaviors for acetate (OAc − ), which however, are unavailable to chloride (Cl − ), fluoroborate (BF 4 − ), or nitrate (NO 3 − ) anion. CPs 1 and 2 also show ligand-based solid-state fluorescent emissions at room temperature.