Synthesis And Crystal Structure Of Co(Ⅱ) Metal-organic Frameworks Coordination Ploymers With Ethanolamine-bridge

In this thesis, we chose N-methyldiethanolamine(MedeaH2) and different carboxylic acids asthe mixed ligands to synthesize five coordination compounds. These obtained compounds havebeen structurally characterized by single crystal X-ray analysis.Compounds1-5have trinuclear cobalt clusters (Co3) as secondary building units (SBUs).Compound1features the3D microporous framework while compounds2-5show2D sheetstructures. We use the given ethanolamine to stablize the trinuclear cobalt SBUs, and differentcarboxylic acids to tune the final structures of these compounds.Compounds1-5are formulated as below:[Co1.5(MedeaH)(bdc)(bdcH2)0.5]·EtOH (1),（bdcH2=1,4-benzenedicarboxylic acid andMedeaH=N-methyldiethanolamine）[Co1.5(MedeaH)(bpdc)]·(bpdcH2)0.5·EtOH (2),（bpdcH2=4,4’-biphenyldicarboxylicacid）[Co1.5(MedeaH)(oba)]·EtOH (3),（obaH2=4,4’-oxy-bis(benzoic acid)）[Co1.5(MedeaH)(1,4-ndc)2]·EtOH (4),(ndcH2=1,4-napthealenedicarboxylic acid)[Co1.5(MedeaH)2(tda)2]·MeOH (5),(tdaH2=thiophene-2,5-dicarboxylic acid)There are diversified channels with different sizes in these compounds. The trunks of thecarboxylic acids have been established to influence the channel sizes. Comparing the2Dparallelogram channel in2-5, we found that their sizes (26.506×15.015of2>26.968×8.371of3>21.548×13.792of4>17.769×12.271of5) are the consequence ofthe different components of the carboxylic acids.Compound1is constructed from1,4-benzenedicarboxylic acid, which possesses the smallestbulk among the five selected carboxylic acids in this paper. The smallest ligand can assemble theCo3SBUs into the3D framework, and the remainding ones extend the Co3SBUs into the2Dstructures.4,4’-biphenyldicarboxylic acid has the longest distance between two carboxyl groups so thatcompound2has the largest channel sizes in2-5. The special flexibility of4,4’-oxy-bis(benzoicacid) provides compound3with a long and narrow channel.1,4-napthealenedicarboxylic acid is a linear ligand with side benzyl group. However, the anglebetween two carboxyl groups of thiophene-2,5-dicarboxylic acid is152°. The channel sizes of4are larger than those of5.The role of the carboxylic ligands in tuning their channel sizes has been clearly demonstratedaccording to their single crystal X-ray analysis. There are two important points in this paper:1)N-methyldiethanolamine can build up Co3SUBs as the stable node.2) The channel sizes will bedependent on the carboxylic acids.