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A novel fluorescent material that can change its emission properties in response to different external stimuli holds significant importance for the development of sensors, information storage, and encryption materials. In this work, we designed and synthesized two zinc(II) coordination compounds, [Zn(HL)I2]·CH3OH (1) and [Zn(HL)Br2]·CH3OH (2), which exhibit remarkable changes in their emission properties under three different external stimuli. The two compounds were prepared using a simple one-pot method by reacting zinc(II) salts with 4-(N,N-diphenylamino)benzaldehyde and 3-amino-2-pyridinone. Under the stimulation of NH3 vapor, both compounds underwent decomposition, leading to a transformation of their fluorescence from yellow to blue, exhibiting a significant blue-shift of more than 170 nm. After exposure to HCl vapor, the fluorescence color of the two original compounds changed from yellow to red, and the color change could be easily distinguished by the naked eye under UV light irradiation. Then after fumigation with NH3 vapor, the color of both samples changed from red to blue. Based on the high-contrast NH3-responsive properties and HCl-responsive properties, we designed and developed test papers capable of detecting HCl vapor and NH3 vapor. Furthermore, due to the transformation from the crystalline state to the amorphous state during grinding, the two compounds also demonstrated high-contrast mechanochromic luminescence properties. After grinding, the color of the two compounds changes significantly from yellow to orange. [ABSTRACT FROM AUTHOR]

Two new Cd2+ coordination polymers (CPs), namely {[Cd(L)(1,4-PDA)]·0.7(C2H5OH)}n (1) and {[Cd(L)0.5(1,8-NDC)·H2O]}n (2) [L = 1,4-bis(5,6-dimethybenzimidazol-1-yl)-2-butene, 1,4-H2PDA = 1.4-phenylenediacetic acid, 1,8-H2NDC = 1,8-naphthalenedicarboxylic acid], were hydrothermally synthesized and characterized. 1 is a (4,4)-layered structure and further extended into a 3D supramolecular network via π–π stacking interactions. 2 features a 2D (3,4)-connected 3,4L83 framework. 1 and 2 can act as luminescence sensors for detecting acetylacetone (acac) and Fe3+ with high sensitivity, selectivity and recyclability. This is the first dual fluorosensors employing CPs for the detection of Fe3+ and acac. The mechanism for the luminescent sensing of acac and Fe3+ was suggested. [ABSTRACT FROM AUTHOR]

Nowadays, photoactive viologen units have been widely encapsulated in metal-organic frameworks and assembled into multifunctional materials with photochromism and other light regulating properties. A novel host-guest MOF material, {[Zn(bcbpy) 0.5 (IPA)]·CH 3 CN} n (1), has been constructed by a viologen ligand 1,1′-bis((3-carboxylatobenzyl)-4,4′-bipyridinium)-dichloride (H 2 bcbpy·2Cl), isophthalic acid (IPA) and zinc(II) chloride. Complex 1 exhibits UV and X-ray dual photochromism and photo-controlled luminescence properties. Complex 1 also exhibits a temperature-dependent phosphorescence from cyan to yellow when the temperature increases from 77 to 297 K. 1T will be obtained when 1 is heated in air at 230 °C for 30 min, 1T shows less sensitive photochromic property than 1 due to its longer C–H⋯O hydrogen bond distance for electron transfer pathway. In addition, complex 1 has the potential application as an inkless and erasable printing material due to the excellent photochromic property. [Display omitted] • A UV and X-ray dual photochromic complex 1 was synthesized and characterized. • Complex 1 exhibits photo-controlled luminescence properties. • Complex 1 exhibits temperature-dependent phosphorescence properties. • Complex 1 has the potential to be used as an inkless and erasable printing material. [ABSTRACT FROM AUTHOR]

Two new complexes with composition {[Ni(L1)(mip)(H 2 O)]·3.6H 2 O} n (1) and {[Co(L2) 2 (npht)]·H 2 O} n (2) [H 2 mip = 5-methylphthalic acid, H 2 npht = 5-nitrophthalic acid, L1 = 1,3-bis(thiabendazol-1-ylmethyl)benzene, L2 = 1,4-bis(thiabendazol-1-ylmethyl)benzene)] were hydrothermally synthesized and characterized by physicochemical and spectroscopic methods. 1 displays a binuclear [Ni 2 L1 2 (mip) 2 structure and further extends into a 2D layer via O–H⋯O hydrogen bond interactions, 2 holds a 1D zigzag linear chain which is further packed via C–H⋯O hydrogen bond interactions into a 3D supramolecular network. Sensing experiments indicate that both complexes can be as high selectivity and sensitivity fluorescent chemosensors for ethylene glycol and Fe3+/Cu2+. Two new complexes were synthesized under hydrothermal condition. The complex 1 displays a binuclear [Ni 2 L1 2 (mip) 2 structure and further extends into a 2D layer via O–H⋯O hydrogen bond. 2 holds a 1D zigzag linear chain which is further linked through C–H⋯O hydrogen bond into a 3D supramolecular network. Sensing experiments indicate that both compounds can be used as highly selective and sensitive fluorescent chemosensors for ethylene glycol and Fe3+/Cu2+. Image 1 • Two bis(thiabendazole) complexes were synthesized and characterized. • 1 and 2 are packed into 2D/3D supramolecular networks by hydrogen bonding. • 1 and 2 exhibit highly sensitive and selective for detection of ethylene glycol. • 1 and 2 could as good fluorescent chemosensors for Fe3+/Cu2+. [ABSTRACT FROM AUTHOR]

[Display omitted] • Complexes 1 , 2 and 3 exhibit reversible photochromic behavior. • Complexes 1 , 2 and 3 exhibit long-lived persistent phosphorescence. • Complex 2 exhibits excitation wavelength dependent fluorescence. • Three complexes show great potential in data encryption and anticounterfeiting. • 2 was fabricated in inkless printing performance and information transmission. Long persistent luminescence materials have wide application prospects in the fields of optical communication, sensors, and anticounterfeiting. Recently, some researchers have proved the feasibility of charge transfer effect in the construction of visible light excited room temperature phosphorescence (RTP) materials. However, materials with electronic effects require elaborate design to exhibit long-lived phosphorescence. Herein, a series of coordination compounds based on viologen ligand HL⋅Cl (4-carboxybenzyl)-4,4′-bipyridinium chloride) and Zn2+ with benzoic acid derivatives (o- , m- , p- phthalic acid) were reported. They exhibit not only reversible photochromic properties, but also long-lived persistent phosphorescence. Three complexes possess different structures through different auxiliary ligands with different optical physical properties. Complex 1 exhibits dynamic phosphorescence emission at low temperatures. Interestingly, we synthesized the first viologen complex (complex 2) with excitation wavelength dependent fluorescence, and the emission color gradually changed from blue to red with the increase of excitation wavelength. In addition, the applications of three complexes in data encryption and anticounterfeiting are further demonstrated. This work not only presents coordination compounds with dynamic afterglow materials, excitation wavelength- and time-dependent emission properties, but also provides a new strategy for the charge transfer effect in visible light-excited RTP materials. [ABSTRACT FROM AUTHOR]

A novel Schiff base ligand HL ·CH 3 COOH with excited-state intramolecular proton transfer (ESIPT) and its zinc (Ⅱ) complex 1 were successfully synthesized, and both of them show high-contrast mechano- and acidochromic luminescence. [Display omitted] A new Schiff base compound (HL ·CH 3 COOH) with D-A structure and its zinc(II) complex (1) were successfully obtained. Due to the introduction of diethylamino and rotatable aromatic rings, both HL ·CH 3 COOH and the complex adopt loosely packing patterns. HL ·CH 3 COOH exhibits keto-form emission due to the excited-state intramolecular proton transfer (ESIPT) process, while complex 1 shows enol-form emission. They all show reversible mechanochromic luminescence (MCL) behavior, which is caused by the phase transformation from crystalline state to amorphous state revealed by Powder X-ray diffraction (PXRD) studies, and is accompanied by the departure of CH 3 COOH molecules for HL ·CH 3 COOH. HL ·CH 3 COOH and complex 1 can be protonated under the fumigation of HCl, resulting in the acidochromic properties, accompanied with the phase transformation. HCl also destroyed the interactions between CH 3 COOH and Schiff base molecules, leading to the departure of acetic acid molecules. More interestingly, HL ·CH 3 COOH also exhibited NH 3 -stimuli response properties due to the prohibition of the ESIPT process. [ABSTRACT FROM AUTHOR]

Multistimuli responsive materials based on the viologen coordination polymers have attracted much interest in the past few years due to the increasing demand for smart materials. In this paper, based on a viologen ligand 1-(3-carboxybenzyl)- 4,4′-bipyridinium chloride (Hcbbpy) and zinc(II) ion, a new crystalline complex, namely, {[Zn(cbbpy)Cl 2 ]·H 2 O} n (1) has been designed and synthesized. In complex 1 , every cbbpy ligand as a bridge links two Zn2+ ions via carboxylate O atom and pyridine N atom to extend to a 1D zigzag chain. The 1D chains are extended to 3D supramolecular structure through π···π stacking and hydrogen bonding. More importantly, 1 exhibits fast photochromic behaviors in response to UV and X-ray due to the formation of viologen radicals. Complex 1 also shows photo-modulated luminescence property in the solid state. In addition, complex 1 can be deposited on filter paper and displays the potential application as inkless print material. [Display omitted] • A new viologen complex was successfully synthesized and characterized. • Complex 1 shows fast response to UV light and X-ray irradiation. • Complex 1 can be deposited on filter paper and displays as inkless print material. [ABSTRACT FROM AUTHOR]