A two-dimensional coordination polymer, [Mn3(HEBTC)2(DMSO)6] (1), has been achieved by a solvothermal reaction of Mn2+ with 1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylic acid (H4EBTC). The layer of a coordination polymer is composed of trinuclear Mn2+ clusters linked by HEBTC3− ligands to form a (3,6)-connected topological net. CP 1 with paramagnetic Mn2+ ions shows dual emissions centered at 397 and 468 nm in the solid state under ambient conditions with respectable quantum yields of 15.3% (397 nm) and 12.3% (468 nm). The dual emissions arise from n ← π* transition in HEBTC3− and MLCT between HEBTC3− and Mn2+ centers.

A coordination polymer (CP) of Mg2+ with 1,3,5-benzenetricarboxylate (BTC3−) was synthesized using a solvothermal method. The Mg-CP, with a formula of Mg3(BTC)(HCOO)3(DMF)3, crystallizes in the trigonal space group P, with cell parameters of a = b = 13.972(5) Å, c = 8.090(5) Å and V = 1367.6(11) Å3, and shows a lamella structure built from planar rosette-type hexanuclear architectures. The Mg-CP emits intense blue fluorescence arising from π* → π transition of intra-ligand of BTC3− with 21.69% quantum yield, yet it exhibits poor stability to water. The composites of Mg-CP with hydrophobic polyvinylidene fluoride (PVDF) were sequentially prepared by mechanically mixed, tableted and annealed processes, which showed good compatibility between Mg-CP and PVDF, high hydrostability, and intense blue emission. This study suggests a simple but efficient method to solve the drawbacks of some functional CPs unstable to water and to promote them as practical applications in the field of functional materials.

A highly thermally stable CP/MOF, comprised of Mg2+ and H2EBTC2− with the formula of [Mg(H2EBTC)(DMF)2], emits dual band luminescence centered at 376 and 555 nm. The former is assigned to the fluorescence of H2EBTC2− and the latter with 1.63 μs decay lifetime and large Stokes shifts corresponds to the phosphorescence of H2EBTC2−. To the best of our knowledge, this is the first time the ligand-based phosphorescence in a CP/MOF without any heavy atom at room temperature has been observed.

A family of novel lanthanide metal–organic frameworks (MOFs) with formula [Ln2(EBTC)1.5(CH3OH)4]·6H2O [EBTC4− = 1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate, Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8) and Dy (9)], have been synthesized via solvothermal reaction. All compounds are isostructural, crystallized in the monoclinic space group P21/n, and show a three-dimensional (4,6)-connected network with Schläfli symbol of {310}. Photoluminescent measurements indicated that 1 and 7 emit the luminescence originating from the intraligand π←π* transition, 2 shows the broadband emission due to allowed 4f–5d transitions, and 4–9 show the emission of typical lanthanide f–f transition via the ligand “antenna effect” in the solid state at ambient temperature. Interestingly, compounds 6 and 8 showed microsecond time-scale fluorescence lifetimes with 0.84 ms for 6 and 0.39 ms for 8, respectively. Such unique spectroscopy features may have applications in biomacromolecule research.

Two ferrocene–isocoumarin conjugated molecules, methyl 3-ferrocenyl-1-oxo-1H-isochromene-6-carboxylate (Fc-Icm) and 3,8-bisferrocenylpyrano[3,4-g]isochromene-1,6-dione (BFc-PIcm), have been synthesized through the acid-prompted regioselective oxidative cyclization from dimethyl 2-(ferrocenylethynyl)terephthalate (Fc-TP) and dimethyl 2,5-bis(ferrocenylethynyl)terephthalate (BFc-TP), respectively. Single-crystal X-ray diffraction, together with the density functional theory (DFT) calculations, shows that the ferrocene–isocoumarin conjugated compounds display better coplanarity than the corresponding ferrocenylethynyl terephthalates. All the compounds exhibit characteristic MLCT, ICT and π–π* transitions in the UV-visible range in solution, and Fc-Icm and BFc-PIcm show higher oscillator strength of the absorption than Fc-TP and BFc-TP, which are verified by time-dependent DFT (TDDFT) theoretical calculations. The electrochemical properties are studied by cyclic voltammetry (CV), which are also in accord with the theoretical calculations.

•Three zinc MOFs based on H4EBTC with/without an auxiliary ligand are synthesized.•Zn(II) ions and carboxylates in different MOFs show different coordination modes.•The three MOFs are 3D microporous coordination polymers with intriguing topologies.•MOFs 1 and 3 exhibit good photoluminescence around the blue-violet region.Three novel microporous zinc MOFs, [Zn3(EBTC)2]∙2(CH3)2NH2∙ 0.5DMSO∙3H2O (1), [Zn(EBTC)0.5(BPY)]∙2DMSO∙0.5DMF∙2H2O (2) and [Zn2(EBTC)(BPP)2]∙3DMSO∙2DMF∙5H2O (3) (EBTC = 1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate, BPY = 4,4′-bipyridine, BPP = 1,3-bi(4-pyridyl)propane), have been synthesized under solvothermal conditions. The versatile coordination modes of EBTC are the key to such diverse MOFs. The results of X-ray single diffraction analyses indicate that 3D microporous MOF 1 with fla topology possesses 2D [Zn3(EBTC)2]∞ layer built from 1D double-chain-like motif containing trinuclear [Zn3(COO)8]2 − SBUs, in which the two phenyls of EBTC are almost perpendicularly arranged. Compound 2 is a 3D layer-pillar structure with Zn(II) ions bridged by planar EBTC to generate 2D [Zn(EBTC)0.5]∞ sheet, and the 2D sheets are further pillared by rigid BPY to form a 3D porous framework with fsc topology. Complex 3 exhibits a 3D 2-fold interpenetrating framework with (4.64.8)2(42.64) topology, in which the flexible BPP links the 1D [Zn2(EBTC)]∞ ladder to form a 2D [Zn2(EBTC)(BPP)2]∞ structure with large 1D channels, which leads the flexible 2D framework to 2-fold interpenetration and forms a 3D porous network. Complexes 1 and 3 exhibit good luminescent properties around the blue-violet region.Three novel zinc microporous MOFs with intriguing topologies have been synthesized by the self-assembly of H4EBTC with/without the corresponding auxiliary ligand of BPY/BPP, where Zn(II) modulates its coordination geometry from octahedron and tetragonal pyramid (1), trigonal bipyramid (2) to tetrahedron coordination (3) geometry as the carboxylates in EBTC adopt different coordination modes to meet the coordination requirement of the MOFs' rigidity/flexibility. MOFs 1 and 3 exhibit good photoluminescence around the blue-violet region.

Three porous supramolecular isomers (IZE-1, IZE-2, and IZE-3) with the same framework component [Zn2(EBTC)(H2O)2] (EBTC = 1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate) were successfully constructed by finely tuning the reaction condition. Although both IZE-1 and IZE-2 are constructed from the linear EBTC subunits and one kind of regular [Zn2(CO2)4] paddlewheels, their frameworks exhibit two different (3,4)-c net of fof (sqc1575) and sqc1572, respectively, resulting in cavities with different size and shape. However, as for isomer IZE-3, the EBTC ligands are bent and one-half of the [Zn2(CO2)4] paddlewheels are distorted, leading to a novel (3,4,4)-c hyx net with point symbol (6.72)4(62.82.102)(72.82.112) and vertex symbol (6.7.7)4(72.72.8.8.12.12)(6.6.8.8.102.102). Quantum chemical calculations by DFT indicate that the three isomers have very close thermodynamic stabilities, which may explain that subtle condition change leads to variation of the frameworks. Further theoretical semiempirical investigation on the interactions between solvent molecules and compounds shows different hydrogen binding patterns in good agreement with the experimental observations. Furthermore, they exhibit good solid-state luminescence properties with long lifetime.

Two coordination polymers, [Zn(EDDT)0.5(H2O)2] (1) and [Zn(EDDT)0.5(BPE)]⋅xG (2) (EDDT = 2,2’-(ethyne-1,2-diyl)diterephthalate, BPE = 1,2-bi(4-pyridyl)ethane, G = guest molecule), were solvothermally synthesized from the rigid planar linker of EDDT and the coligand of BPE, respectively, in which complex 1 displays 2D [Zn(EDDT)0.5] coordination layer, and the resulting 3D supramolecular network is formed via interlayer H-bonding interactions, whereas complex 2 exhibits an intriguing micropourous framework via the coordination of auxiliary ligand BPE. Interestingly, both of them show enhanced strong blue luminescence.Two novel coordination polymers, 2D layer motif of [Zn(EDDT)0.5 ∙ 2H2O] (1) and 3D microporous network of [Zn(EDDT)0.5∙(BPE)]⋅xG (2), built from the rigid planar ligand 2,2'-(ethyne-1,2-diyl)diterephthalate (EDDT) and the pillaring auxiliary ligand 1, 2-bi(4-pyridyl)ethane (BPE), exhibit enhanced strong solid-state luminescence.Highlights► Zinc coordination polymers built from rigid planar tetracarboxylate ligand of 2, 2'-(ethyne-1, 2-diyl)diterephthalate (EDDT). ► 2D layered or 3D micropourous supramolecular network. ► Strong blue emission in the solid state at room temperature.

Two novel lanthanide coordination polymers, [Eu2(EBTC)(DMF)5(NO3)2]·DMF (1) and [Eu2(BBTC)1.5(CH3OH)2(H2O)2]·7DMF·HNO3 (2) (EBTC4− = 1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate; BBTC4− = 1,1′-butadiynebenzene-3,3′,5,5′-tetracarboxylate), were successfully synthesized from conjugated ligands of EBTC4− and BBTC4−. Although the two tetracarboxylate ligands have similar structures, their different rigidity/flexibility results in quite different networks upon complexation. Complex 1 has a two-dimensional (2-D) layered structure with two crystallographically independent Eu3+ ions, one in a distorted monocapped square-antiprism and the other in a distorted square-antiprism coordination geometry. Complex 2 exhibits a three-dimensional (3-D) porous framework, with one type of Eu3+ in a distorted square-antiprism and the other in a trigondodecahedron environment. Both 1 and 2 emit the intensely red characteristic luminescence of Eu3+ ion at room temperature, with a long lifetime of up to 1.3 and 0.7 ms, respectively, during which the ligand emission of EBTC4−/BBTC4− was quenched by the Eu3+ ion, indicating the existence of efficient energy transfer between the conjugated ligand of EBTC4−/BBTC4− and the Eu3+ ion. Thus, both EBTC4− and BBTC4− are ideal ligands with an “antenna” effect for the Eu3+ ion. The two complexes show the single-ion magnetic behaviors of Eu3+ with strong spin–orbit coupling interactions even if there are shorter distances (5.714 Å for 1versus 4.275 and 5.360 Å for 2) between the neighboring Eu3+ ions connected by oxygen atoms of the tetracarboxylates.

Two stable supramolecular microporous polymers with double-layer structures, [Co(AIP)(BPY)0.5 · H2O]n · 2nH2O (1) and [Ni(AIP)(BPY)0.5 · H2O]n · 2nH2O (2), were constructed from AIP (5-aminoisophthalate) and BPY (4,4′-bipyridine) under hydrothermal conditions. Both of them exhibit rarely reported (3,4)-connected (63)(658) topology and interesting water-induced reversible transformation properties that are confirmed by PXRD studies.Two stable supramolecular microporous polymers with rarely (3,4)-connected (63)(658) topology, [Co(AIP)(BPY)0.5 · H2O]n · 2nH2O (1) and [Ni(AIP)(BPY)0.5 · H2O]n · 2nH2O (2), (AIP = 5-aminoisophthalate, BPY = 4,4′-bipyridine), have been synthesized under hydrothermal conditions. Both of them represent interesting water-induced reversible transformation properties confirmed by PXRD studies.

Two donor−acceptor molecules with different π-electron conjugative units, 1-((10-methyl-10H-phenothiazin-3-yl)ethynyl)anthracene-9,10-dione (AqMp) and 1,1′-(10-methyl-10H-phenothiazine-3,7-diyl)bis(ethyne-2,1-diyl)dianthracene-9,10-dione (Aq2Mp), have been synthesized and investigated for their photochemical and electrochemical properties. Density functional theory (DFT) calculations provide insights into their molecular geometry, electronic structures, and properties. These studies satisfactorily explain the electrochemistry of the two compounds and indicate that larger conjugative effect leads to smaller HOMO−LUMO gap (Eg) in Aq2Mp. Both compounds show ICT and π → π* transitions in the UV−visible range in solution, and Aq2Mp has a bathochromic shift and shows higher oscillator strength of the absorption, which has been verified by time-dependent DFT (TDDFT) calculations. The differences between AqMp and Aq2Mp indicate that the structural and conjugative effects have great influence on the electronic properties of the molecules.

Two ferrocene–isocoumarin conjugated molecules, methyl 3-ferrocenyl-1-oxo-1H-isochromene-6-carboxylate (Fc-Icm) and 3,8-bisferrocenylpyrano[3,4-g]isochromene-1,6-dione (BFc-PIcm), have been synthesized through the acid-prompted regioselective oxidative cyclization from dimethyl 2-(ferrocenylethynyl)terephthalate (Fc-TP) and dimethyl 2,5-bis(ferrocenylethynyl)terephthalate (BFc-TP), respectively. Single-crystal X-ray diffraction, together with the density functional theory (DFT) calculations, shows that the ferrocene–isocoumarin conjugated compounds display better coplanarity than the corresponding ferrocenylethynyl terephthalates. All the compounds exhibit characteristic MLCT, ICT and π–π* transitions in the UV-visible range in solution, and Fc-Icm and BFc-PIcm show higher oscillator strength of the absorption than Fc-TP and BFc-TP, which are verified by time-dependent DFT (TDDFT) theoretical calculations. The electrochemical properties are studied by cyclic voltammetry (CV), which are also in accord with the theoretical calculations.

A highly thermally stable CP/MOF, comprised of Mg2+ and H2EBTC2− with the formula of [Mg(H2EBTC)(DMF)2], emits dual band luminescence centered at 376 and 555 nm. The former is assigned to the fluorescence of H2EBTC2− and the latter with 1.63 μs decay lifetime and large Stokes shifts corresponds to the phosphorescence of H2EBTC2−. To the best of our knowledge, this is the first time the ligand-based phosphorescence in a CP/MOF without any heavy atom at room temperature has been observed.

A coordination polymer (CP) of Mg2+ with 1,3,5-benzenetricarboxylate (BTC3−) was synthesized using a solvothermal method. The Mg-CP, with a formula of Mg3(BTC)(HCOO)3(DMF)3, crystallizes in the trigonal space group P, with cell parameters of a = b = 13.972(5) Å, c = 8.090(5) Å and V = 1367.6(11) Å3, and shows a lamella structure built from planar rosette-type hexanuclear architectures. The Mg-CP emits intense blue fluorescence arising from π* → π transition of intra-ligand of BTC3− with 21.69% quantum yield, yet it exhibits poor stability to water. The composites of Mg-CP with hydrophobic polyvinylidene fluoride (PVDF) were sequentially prepared by mechanically mixed, tableted and annealed processes, which showed good compatibility between Mg-CP and PVDF, high hydrostability, and intense blue emission. This study suggests a simple but efficient method to solve the drawbacks of some functional CPs unstable to water and to promote them as practical applications in the field of functional materials.

A family of novel lanthanide metal–organic frameworks (MOFs) with formula [Ln2(EBTC)1.5(CH3OH)4]·6H2O [EBTC4− = 1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate, Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8) and Dy (9)], have been synthesized via solvothermal reaction. All compounds are isostructural, crystallized in the monoclinic space group P21/n, and show a three-dimensional (4,6)-connected network with Schläfli symbol of {310}. Photoluminescent measurements indicated that 1 and 7 emit the luminescence originating from the intraligand π←π* transition, 2 shows the broadband emission due to allowed 4f–5d transitions, and 4–9 show the emission of typical lanthanide f–f transition via the ligand “antenna effect” in the solid state at ambient temperature. Interestingly, compounds 6 and 8 showed microsecond time-scale fluorescence lifetimes with 0.84 ms for 6 and 0.39 ms for 8, respectively. Such unique spectroscopy features may have applications in biomacromolecule research.

Two novel lanthanide coordination polymers, [Eu2(EBTC)(DMF)5(NO3)2]·DMF (1) and [Eu2(BBTC)1.5(CH3OH)2(H2O)2]·7DMF·HNO3 (2) (EBTC4− = 1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate; BBTC4− = 1,1′-butadiynebenzene-3,3′,5,5′-tetracarboxylate), were successfully synthesized from conjugated ligands of EBTC4− and BBTC4−. Although the two tetracarboxylate ligands have similar structures, their different rigidity/flexibility results in quite different networks upon complexation. Complex 1 has a two-dimensional (2-D) layered structure with two crystallographically independent Eu3+ ions, one in a distorted monocapped square-antiprism and the other in a distorted square-antiprism coordination geometry. Complex 2 exhibits a three-dimensional (3-D) porous framework, with one type of Eu3+ in a distorted square-antiprism and the other in a trigondodecahedron environment. Both 1 and 2 emit the intensely red characteristic luminescence of Eu3+ ion at room temperature, with a long lifetime of up to 1.3 and 0.7 ms, respectively, during which the ligand emission of EBTC4−/BBTC4− was quenched by the Eu3+ ion, indicating the existence of efficient energy transfer between the conjugated ligand of EBTC4−/BBTC4− and the Eu3+ ion. Thus, both EBTC4− and BBTC4− are ideal ligands with an “antenna” effect for the Eu3+ ion. The two complexes show the single-ion magnetic behaviors of Eu3+ with strong spin–orbit coupling interactions even if there are shorter distances (5.714 Å for 1versus 4.275 and 5.360 Å for 2) between the neighboring Eu3+ ions connected by oxygen atoms of the tetracarboxylates.