The Application Of Polymer Fluorescence Sencors In Molecular Recognition

Chirality is one of the most fundamental properties of natural biological phenomena. More and more efforts have been devoted to the area of finding effective chiral molecular recognition sensors. Among various kinds of detecting methods, chiral fluorescence sensors have the advantages such as simple operation, none destroy to the samples, rapid screening and high sensitivity, which make them one of the research hotspots.Chiral BINOL plays a key role in chemistry, its C2 symmetry, easy to modify and moderate fluorescence make it widely applicable in chiral fluorescence sensors. Circular dichroism (CD) spetra can generate positive/negative Cotton effects from the chirality of guest molecules, and thus recognize the comformation of the samples. The whole process does not require the sensors to be chiral, which can greatly reduce the difficulty for the design of CD sensors.Compared with small organic molecules, those conjucated polymers-based chiral fluorescence sensors can exhibit high sensitivity to external structural perturbations and electron density changes of the delocalizable π-electronic chain backbone while they interact and form complexes with analytes, which can amplify the change of fluorescence and thereby improve the detecting sensitivity. This paper mainly foucuses on the application of polymers-based fluorescence senors and CD sensors in the area of chiral molecular recognition.The first work reported a new way of introducing amino group into the 3,3’sites of BINOL with less steps in higher yield, the product was used as one of the monomers to synthesis a polymer-based chiral fluorescence sensor 2-P1 via Schiff base formation, which can show high enantioselectivity to phenylalaninol. The D-phenylalaninol can induce the solution of the polymer sensor to generate a larger fluorescence enhancement with ef value as high as 8.99. In addition, the difference of fluorescence change caused by the phenylalaninol enantiomers can be directly detected by the naked eyes under a commercially available UV lamp.The second work synthesized two BINOL-based chiral monomers via click reaction, and then got two ionic polymer sensors 3-P1 and 3-P2, respectively. Both of them can show obvious fluorescence enhancement to D-Trp" with good enantioselectivity, the ef values are 6.25 and 7.87, respectively. Interestingly, L-or D-Trp" can induce the fluorescence of 3-P2 to show a large red-shift, and the different fluorescence influences can be seen by the naked eyes under a commercially UV lamp.The third work mainly got a BINOL-based chiral polymer sensor 4-P1 via click reaction, which can successfully enantioselective the conformation of phenylalaninol, D-phenylalaninol can induce a lager fluorescence enhancement of the polymer sensor solution with ef value up to 2.99. To the best of our knowledge, this is the first example that a polymer directly generated from click reaction was used as fluorescence sensor in chiral molecular recognition.The last work synthesized an archiral polymer 5-P1 incorporating tridentate ligand and then coordinated with Cu2+ to in situ form an 1:1 Cu2+ -containing polymer complex 5-P2 in solution, which can show obvious fluorescence turn-on behavior only toward histidine among various kinds of amino acids. It can also show good enantioselectivity to histidine enantiomers by means of CD spectra with L-histidine corresponding to the negative Cotton effect and D-histidine corresponding to the positive Cotton effect. Meanwhile, the modular molecule of 5-P2 cannot exhibit effective CD signals toward histidine.