Zhonghai Ni

A new TICT and AIE-active tetraphenylethene-based Schiff base with reversible piezofluorochromism

A new tetraphenylethene-based Schiff base N-5-nitrosalicylidene-4-tetraphenylethenylamine (NSTPE) was synthesized based on 4-tetraphenylethenylamine and 5-nitrosalicylaldehyde, and its structure was fully characterized by 1H NMR, 13C NMR, MS and single crystal X-ray diffraction analysis. The study of optical properties shows that the emission exhibits an interesting “on–off–on” switching property with a U-shaped tendency when adding water into the tetrahydrofuran solution of NSTPE, showing twisted intramolecular charge transfer (TICT) and aggregation-induced emission (AIE) characteristics. Moreover, the compound exhibits reversible piezofluorochromic properties.

N, S and P-ternary doped carbon nano-pore/tube composites derived from natural chemicals in waste sweet osmanthus fruit with superior activity for oxygen reduction in acidic and alkaline media

To promote the practical application of novel heteroatom-doped carbon electrocatalysts for the oxygen reduction reaction (ORR) in fuel cells, in this work, low-cost nitrogen (N), sulfur (S) and phosphorus (P)-ternary doped carbon nano-pore/tube composites (NSP-CNPTCs) were synthesized by natural, cheap and environment-friendly N, S and P-containing chemicals extracted from waste sweet osmanthus fruit and a certain amount of dicyandiamide with ferric sulfate as a catalyst. Electrochemical tests demonstrated that the as-prepared NSP-CNPTCs exhibited superior ORR activity in both acidic and alkaline media, showing a new approach for utilizing natural heteroatom-containing chemicals in all heteroatom-rich biomasses to synthesize value-added heteroatom-doped carbon electrocatalysts in future fuel cells.

Substituent group tuned tri- and binuclear porphyrin-based cyanide-bridged bimetallic complexes: synthesis, crystal structures and magnetic properties

A series of six cyanide-bridged heterobimetallic complexes including {[M(L)2]2[Mn(TPP)]}[Mn(TPP)(MeOH)2]·xH2O·yMeOH {L = 1,2-bis(pyridine-2-carboxamido)-4-methylbenzenate (bpb2−), M = Cr (1), Co (2); L = 1,2-bis(pyridine-2-carboxamido)benzenate (bpmb2−), M = Cr (3), Co (4); TPP = meso-tetra(phenyl)porphyrin} and {[M(bpb)(CN)2][Mn(TClPP)(MeOH)]}·xH2O·yMeOH {M = Cr (5), Co (6), TClPP = meso-tetra(4-chlorophenyl)porphyrin} were designed and synthesized with two manganese(III)–porphyrin compounds and four pyridinecarboxamide dicyanidemetalates as building blocks. X-ray diffraction analysis reveals that compounds 1–4 containing the [Mn(TPP)]+ ion connect two dicyanide-containing [M(L)(CN)2]− anions to form the anionic trinuclear sandwich-like MIII–MnIII–MIII molecular moiety with the one [Mn(TPP)(CH3OH)2]+ segment as a balance cation. The MIII–MnIII complexes 5 and 6 show a dinuclear molecular conformation comprised of [M(bpb)(CN)2]− and [Mn(TClPP)(MeOH)]+ ions bridged by one cyanide group linking the MnIII ion. Investigation of magnetic properties of the cyanide-bridged Cr–Mn complexes reveals the weak antiferromagnetic interaction between MnIII and CrIII magnetic centers with JMnCr = −0.116(2), −0.092(2) and −0.86(2) cm−1 for 1, 3, and 5, respectively.

A new near-infrared ratiometric fluorescent probe for hydrazine

It is important to develop fluorescent probes for rapid, selective, and sensitive detection of highly toxic hydrazine in both environmental and biological science. In this text, under mild conditions, a novel near-infrared (NIR) ratiometric and on–off fluorescent probe 1 was synthesized based on hemicyanine and coumarin derivatives, which can detect hydrazine with high selectivity and anti-interference over other amines, biological species, anions and metal ions. The limit of quantification (LOQ) value was 0–400 μM and the detection limit could be as low as 560 nM.

A series of tetraphenylethene-based benzimidazoles: syntheses, structures, aggregation-induced emission and reversible mechanochromism

Four tetraphenylethene-based benzimidazoles 5,6-R-2-(4-tetraphenyletheneyl)-1H-benzo[d]imidazoles (R = H (2a), Cl (2b), Br (2c) and CH3 (2d)) were conveniently synthesized in high yields by the cyclization reaction of 4-tetraphenylenthenealdehyde with phenylenediamines. These compounds were structurally characterized and their properties were analyzed by spectroscopy, electrochemistry, X-ray diffraction, thermal stability and theoretical studies. Single crystal X-ray diffraction analyses indicate that their molecular structures in the aggregated state are highly twisted conformations and there exist obvious cavities and/or interface gaps in their crystal packing structures. These four compounds exhibit typical aggregation-induced emission (AIE) properties with relatively high absolute fluorescence quantum yields (30.6–67.5%). These compounds also exhibit reversible mechanochromism behaviors with emission changes between light blue and yellow-green, which are due to the reversible morphological transformation between unconsolidated crystalline state and amorphous state. They are thermally stable with decomposition temperatures above 340 °C.

A new series of pyrenyl-based triarylamines: syntheses, structures, optical properties, electrochemistry and electroluminescence

Five dipyrenyl-based triarylamines N-p-(R)-phenyl-N,N-dipyrenyl-1-amine (R = H (2a), CH3 (2b), OCH3 (2c), F (2d), NO2 (2e)) and one tripyrenyl-based triarylamine N,N-bis(7-tert-butylpyren-1-yl)-N-pyrenyl-1-amine (3py) were successfully synthesized by copper- and palladium-catalyzed coupling reactions in high yields. These compounds were structurally characterized and their photoelectric properties were analyzed by spectroscopy, electrochemical and theoretical studies. Moreover, the structures of 2b, 2c and 2d were determined by single-crystal X-ray diffraction analysis, indicating that the three compounds are all twisted paddle-like structures with a nitrogen atom as the linking center and the substituent attached to the para position of the benzene ring has an important effect on the intermolecular interactions. Compounds 2a–2d and 3py show green fluorescence emissions with excellent absolute fluorescence quantum yields in toluene (66.06–86.06%). Compound 2e displays a faint emission with a very low quantum yield because of the effect of the strong electron-withdrawing nitro group. They are thermally stable with decomposition temperatures above 355 °C. Organic light-emitting diodes incorporating the materials 2c and 2d as non-doped emitters were fabricated.

Synthesis, crystal structure, and magnetism of a two-dimensional copper(II) complex with single end-to-end and double end-on azide bridges

A new azido-bridged copper(II) complex, [Cu(dmp)(µ 1,1-N3)(µ 1,3-N3)] n (1) (dmp = 3,5-dimethylpyrazole), has been structurally and magnetically characterized. X-ray diffraction analysis indicates that the compound consists of double end-on (EO) azido-bridged dimers which are linked by single end-to-end (EE) azide bridges to form a 2-D layer-like structure. Magnetic investigation demonstrates an overall ferromagnetic interaction in 1 and both azide bridges (EE and EO) transmit ferromagnetic coupling. At low temperature (T < 2.5 K), the compound exhibits some metamagnetic behavior.

Two Cyanide-Bridged Heterometallic One-Dimensional Chain Complexes Constructed by Hydrogen Bond Interactions: Synthesis, Crystal Structures, and Magnetic Properties

Two trinuclear cyanide-bridged heterometallic Ni(II)– Mn(III) complexes {[Mn(L1)(H2O)]2[Ni(CN)4]} 2H2O (1) and {[Mn(L2)(H2O)]2[Ni(CN)4]} (2) (L1 = N,N-ethylene-bis(3-methoxysalicylideneiminate; L2 = N,N-ethylene-bis(3-ethoxysalicylideneiminate) have been obtained by using [Ni(CN)4]2− and two manganese(III) compounds containing bicompartimental Schiff base ligands as assembling segments. X-ray diffraction reveals that the two cyanide-bridged trinuclear complexes are self-complementary through intermolecular O–H…O hydrogen bond interactions formed by a coordinated aqua ligand from one molecule and the four phenolic oxygen atoms from the neighboring one, giving a supramolecular one-dimensional chain structure. Investigation of the magnetic susceptibilities of these two complexes reveals the overall weak antiferromagnetic interactions between the adjacent Mn(III) ions.

Colorimetric and fluorescent detection of hydrazine with high sensitivity and excellent selectivity

It is critical to develop probes for rapid, selective, and sensitive detection of the highly toxic hydrazine in both environmental and biological science. In this work, under mild condition, a novel colorimetric and off-on fluorescent probe was synthesized for rapid recognition of hydrazine with excellent selectivity over other various species including some biological species, metal ions and anions. The limit of quantification (LOQ) value was 1.5×10-4M-3.2×10-3M (colorimetric method) and 1.5×10-4M-3.2×10-3M (fluorescent method) with as low as detection limit of 46.2μM.