Two‐Photon‐Induced Fluorescence of Isomorphic Nucleobase Analogs |
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Authors: | Dr Richard S K Lane Rosemary Jones Dr Renatus W Sinkeldam Prof Dr Yitzhak Tor Dr Steven W Magennis |
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Institution: | 1. School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL (UK);2. Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (USA);3. Current Address: School of Chemistry, The University of Glasgow, Joseph Black Building, University Avenue, Glasgow, G12 8QQ (UK) |
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Abstract: | Five isomorphic fluorescent uridine mimics have been subjected to two‐photon (2P) excitation analysis to investigate their potential applicability as non‐perturbing probes for the single‐molecule detection of nucleic acids. We find that small structural differences can cause major changes in the 2P excitation probability, with the 2P cross sections varying by over one order of magnitude. Two of the probes, both thiophene‐modified uridine analogs, have the highest 2P cross sections (3.8 GM and 7.6 GM) reported for nucleobase analogs, using a conventional Ti:sapphire laser for excitation at 690 nm; they also have the lowest emission quantum yields. In contrast, the analogs with the highest reported quantum yields have the lowest 2P cross sections. The structure‐photophysical property relationship presented here is a first step towards the rational design of emissive nucleobase analogs with controlled 2P characteristics. The results demonstrate the potential for major improvements through judicious structural modifications. |
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Keywords: | fluorescence multiphoton nucleoside ribonucleoside single‐molecule |
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