Synthesis, Characterization And Performance Study Of 5-bromonicotinicate Complexes And Chiral Terpyridyl Function Compounds

The framework material of metal-organic coordination polymers is a kind of new materials with potential applications. In this paper, 5-bromonicotinic acid(Br-a)was selected as the main ligand to assemble with magnetic metal ions such as Fe(II),Ni(II) and Co(II), and consequently four new metal-5-bromonicotinate coordination polymers, namely, [Fe(Br-a)2(H2O)2]n(1), [Ni(Br-a)2]n(2),[Ni(Br-a)(bpy)(H2O)2]n?n(Br-a)?4.5n H2O(3), and [Co2(Br-a)3(bpy)2(OH)]n?n H2O(4)were obtained(bpy = 4,4’-bipyridine). The synthesis methods, structures and related properties of compounds 1–4 have been systematically discussed. Complex 1 has corrugated(4,4) sheets formed by μ-(Br-a) ligands and planar nodes Fe(II), and the further O···Br weak interactions between adjacent layers result in the 3D supramolecular network. As for 2?4, they all built up from(Br-a)–bridged dinuclear subunits, but have very different structure features. Complex 2 is a rare twin-like polymer with(4,4) layers formed by twin paddle-wheel [Ni2(Br-a)4] subunits.Through the bridge coordination of bpy ligands with dinuclear rings [Ni2(Br-a)2] and trigons [Co2(Br-a)3(OH)], 63-topological cationic layers with nanosized grids of 3 and chiral ladder-type double chains of 4 formed, respectively. The free counter anions Br-a were captured in the nanometer grids of 3. Notably, halogen-related interactions play an important role in the formation of 3D metallosupermolecules 1-4. The results of thermal stability investigation upon those synthesized crystalline products suggest that the polymeric frameworks are stable up to 270 °C. Moreover, the magnetic studies of 2 and 4 indicate that there exist weaker antiferromagnetic interaction in the paddle-wheel [Ni2(Br-a)4] exchanged only by carboxyl bridges whereas stronger antiferromagnetic coupling in the trigon [Co2(Br-a)3(OH)] propagated by the carboxyl bridge, and especially by μ-OH bridge.Terpyridine has strong fluorescence emission. Therefore, the design and synthesis of functional terpyridine compounds based on terpyridine group is of great importance in the development of light-emitting materials. In this thesis, four chiral terpyridine compounds, namely,(L)-2-((4-([2,2’:6’,2’’-terpyridin]-4’-yl)benzyl)amino)-propanehydrazide [(L)-T~1],(D)-2-((4-([2,2’:6’,2’’-terpyridin]-4’-yl)benzyl)amino)propanehydrazide [(D)-T~2],(L)-1-(4-([2,2’:6’,2’’-terpyridin]-4’-yl)benzyl)-3-((2-hydroxybenzylidene)amino)-2-(2-hydroxyphenyl)-5-methylimidazolidin-4-one [(L)-T~3], and(D)-2-((4-([2,2’:6’,2’’-terpyridin]-4’-yl)benzyl)amino)-N’-(2-hydroxybenzylidene)prop anehydrazide [(L)-T~4], were designed and synthesized. The structures of these compounds were determined by infrared spectra, nuclear magnetic resonance spectra(NMR), and high resolution mass spectrometry, etc. Their fluorescence and Optical rotation properties were also studied. Optical rotation tests show that the specific optical rotations of(L)-T~1 and(D)-T~2 are equal in values but with reverse signs,indicating enantiomers each other. As for their hydrazone compounds(L)-T~3 and(D)-T~4 resulting from the condensation reactions with salicylaldehyde, however, they have very large positive values in specific optical rotations, indicating that they are diastereoisomers and that there are derived new spiral chirality in their molecules in addition to the chiral carbon atoms. Very interestingly, compounds(L)-T~3 and(D)-T~4 were obtained through enantiomorphism isomers(L)-T~1 and(D)-T~2 reacting with salicylic aldehyde in exactly the same experimental condensation conditions but their structures are completely different, being likely due to the hetergeneous chiral carbons controlling the process of organic reactions. Fluorescence results show that compounds(L)-T~1,(D)-T~2,(L)-T~3 and(D)-T~4 all have strong fluorescence emissions in ultraviolet-visible range. Both(L)-T~3 and(D)-T~4 have dual wavelength fluorescence emissions. In particular, the fluorescence emission peaks of(L)-T~3 center at 456 nm and 560 nm, respectively, and the purple and yellow green emissions are a pair of complementary colors, and thereby compound(L)-T~3 can be used as a potential white light material.