Build Functional Complex Multi-aza Macrocyclic Ligand Synthesis, Structure And Properties

With rapid development and playing a key role in energy, materials and life sciences, transition and rare earth metal-organic complexes are one such important type of solid-state materials with great prospects of practical applications. In this paper, we selected functional metal ions and the ligands of N-heterocyclic compounds for assembling a series of novel metal-organic hybrid material with different structural and functional properties.Zn3(C₁₂H₁₀N₆)₂Cl8·2H₂O [C₁₂H₁₀N₆ = 3,5-di(2-pyridyl)-4-amino-1,2,4-triazole] (1), Cu(C₁₂H₉N₅)₂Cl₂ [C₁₂H₉N₅ = 3,5-di(2-pyridyl)-1,2,4-triazole] (2), Zn(C₁₂H₁₀N₄O)Cl [C₁₂H₁₀N₄O = 2-pyridinecarboxylic acid (pyridin-2-ylmethylene)- hydrazide)] (3), have been synthesized with different ligands derived from 3,6- bis(2-pyridyl)-1,2-dihydro-1,2,4,5-tetrazine. [KNd(bta)₂(H₂O)6]·H₂O (4) has been synthesized using bistetrazolylamine (H₂bta) as ligand. [Ni₂(C₄H₄N₈)₂(C₃H₁₀N₂)₄·8(H₂O)] (5) has been synthesized based on the ligand 3,3'-azobis(1,2,4-triazole). N-salicylidene 3-amino-1,2,4-triazole[C₉H₈N₄O] (6) has been synthesized with 3-amino-1,2,4-trizole and salicylic aldehyde as raw materials. The complexes 1-5 have been characterized by single crystal X-ray diffraction analysis. Compound 6 has been characterized by 1HNMR spectra. In 1, the anion-πinteractions between the Cl- anions of [ZnCl4]2- and theπ-systems of ligand 3,5-di(2-pyridyl)-4-amino-1,2,4-triazole are observed and the anion-π, hydrogen bonding andπ-πstacking interactions link the two complex units of [Zn(C₁₂H₁₀N₆)₂(H₂O)₂]4+ and [ZnCl₄]2- to form a three dimensional supramolecular structure. 2 and 3 exhibit two dimensional supramolecular structures. The rearrangement reaction of 3,6-bis(2-pyridyl)-1,2-dihydro-1,2,4,5-tetrazine was observed in the syntheses of 1-3 and the rearrangement reaction mechanisms in different environment were discussed. 4 is a heteronuclear complex with a novel one-dimensional chain structure and further forming into a three dimensional supramolecular structure through intermolecular hydrogen bonding interactions. In 5, the Ni2+ ions are linked into 1-D chain structure by the bridging ligand of 3,3'-azobis(1,2,4-triazole).The UV-vis, IR, fluorescent spectra for compound 1-6 have been characterized and the results show that these compounds showing interesting fluorescence properties. The solid sample of 1 displays the main maximum emission band at 451 nm; the solid sample of 3 displays the main maximum emission band at 476 nm; the solid sample of 4 exhibits the emission maximum at 412 nm and 5 displays the main maximum emission band at 416 nm; the aqueous solution of 6 displays the main emission band at 500nm,614nm and the solid sample of 6 displays the main emission band at 518 nm,616 nm. 6 has thermochromic and photochromic reactions in aqueous solution under heating or irradiation with 254,365 nm UV light. The multicolor fluorescent imaging for the solid sample and aqueous solution of compound 6 have been observed by a laser scanning confocal microscope and the results show that the compound emits simultaneously green and red fluorescent spectra, further exhibiting photochromic reactions. The multicolor photoluminescence of 6 has been employed to label onion cell and micro-cracked bone and this photochromic fluorophore promise a novel multicolor photoluminescent imaging agent that can be employed to label proteins, DNA and other biomolecules in biological system.