Synthesis And Application Of Binnaphol Derivative Based Enzyme Mimic Receptors

Supramolecular chemistry is a science of study on the intermolecular interactionsbetween two or more chemical species which could form a complicated and orderedsupramolecular system with certain functions. Study on molecular recognition using artificialreceptors to construct the chemical models or biomimetic system is one of the challenges inthe frontiers of bioorganic chemistry and supramolecular chemistry. Some recently studiedenzyme mimic binaphthol derivatives have the function of amino acid chiral conversion, theyalso can be used for enantioselective recognition of chiral1,2-amino alcohols and extractiveseparation of amino acids as well as1,2-amino alcohols are reviewed. Moreover, opticallyactive BINOL and its derivatives have unique chemical properties and chiral inductivefunction because of the C2symmetric axis. When they are introduced into a suitablefunctional group, they can produce strong fluorescence, so they are widely applied toasymmetric catalytic reactions and fluorescence recognition of chiral object. Fluorescencechemosensors are widely used to detect metal ions and anions because of their high selectivity,sensitivity and simplicity. In this thesis, two kinds of different receptors based on binolderivatives were synthesized and investigated for their applications. Firstly, enzyme mimicbinapthol derivatives were synthesized and investigated for their applications in L-aminoacids chiral conversion and1,2-amino alcohols enantioselective recognition. Secondly, twonew chemosensors based on binol derivatives were synthesized and investigated for theirapplications in the detection of copper ion （Cu2+） and fluorin ion （F-）. The details are asfollows:1. The methods of synthesizing receptor were introduced briefly. The application of PLPenzyme mimic binaphthol derivatives in chiral conversion of amino acids andenantioselective recognition of chiral1,2-amino alcohols in recent years were summarized. Inthe ion recognition, binaphthol based chemosensors for anion and cation recognizing in recentyears were summarized.2. Two binaphthol based enzyme mimic reagents2-1and2-2, which containingcyclohexyl urea and guanidinium hydrogen bonding moiety respectively, were synthesizedand characterized. 3. Both molecules not only can be applied to amino acid chirality inversion but also canbe applied to enantioselective recognition of1,2-amino alcohols. The chirality inversioneffects of2-1and2-2for L-α-amino acids to D-α-amino acids were examined by1H NMR inDMSO-d6in the presence of triethylamine. The results showed that2-1and2-2can react withthe tested L-α-amino acids to form corresponding imine and subsequently convert partiallythe amino acid from its L form to D form through an epimerization processes. The chiralityinversion efficiency （KD/KL） of2-2to L-histidine is5.2, the value of （KD/KL） of2-1toL-serine is3.5. The enantioselective recognition effects of2-1and2-2for1,2-amino alcoholwere examined by1H NMR in CDCl3. The enantioselective recognition efficiency（KR/KS）of2-1to2-amino-1-ppropanol is6.25, the value of （KR/KS） of2-2to2-amino-1-butanol is1.97.Comparision of the application of2-1and2-2with those of some known enzyme mimicreagents are also discussed.4. A new metal ion fluorescence sensor4-3was designed and synthesized by introducing4-amino benzo-15-crown-5into the framework of Binol which showed a high selectivitytowards Cu²⁺through fluorescence quenching in CH3CN:HEPES （v:v=1:1）. The bindingstoichiometry of4-3and Cu²⁺is12according to the titration data based onBenesi-Hildebrand plot. The Cu²⁺recognition process of4-3is not significantly influenced byother coexisting metal ions (Hg²⁺, Pb²⁺, Sr²⁺, Ba²⁺, Cd²⁺, Ni²⁺, Co²⁺, Fe²⁺, Mn²⁺, Zn²⁺, Al3+,Mg²⁺, K+, Fe3+, Cr3+, Na+).5. A new anion fluorescence sensor5-1was designed and synthesized by combiningBinol and2-benzimidazolamine which showed a high selectivity towards F-throughfluorescence enhancement in CH3CN. The results of Job’s plot based on a1:2binding modeindicated that sensor5-1and F-formed a1:2stoichiometric complex. This highly selective F-recognition process of5-1is barely influenced by other coexisting anions （F^-, Cl^-, Br^-, I^-,HSO₄^-, NO₃^-, Ac^-）.