| Small organic molecule fluorescent probes have a lot of advantages, such as ease of synthesis, convenient operating, high selectivity and sensitivity, etc. In particular, fluorescent probes can be applied to vivo analysis by fluorescence imaging while the traditional methods do not have this function. Currently, fluorescent probes have become a powerful analytical tool and widely used in many research fields such as biology, medicine and environment, etc. In this paper, based on the common fluorophores and detection mechanisms, a series of fluorescent probes have been designed and synthesized to detect the anions and cations which are toxic and harmful to human and environment. The main work of this paper focuses on the following aspects:1. An "off-on" fluorescent probe (S1) for CN- has been developed, which introduced pyrene as a fluorophore and open-chain carboxyl crown ether as a recognition group. The recognition mechanism of probe 3 for CN- based on the facts that Cu2+ is an effective fluorescence quencher and Cu2+ can form a stable coordination compound with CN-. When Cu2+ was added into a solution of probe S1, it quenched the fluorescence of the solution by PET mechanism, the detection system was in "off" state, after further addition of CN-, CN- snatched Cu2+ from the detection system and formed stable [Cu(CN)x]n- species. As a result, the PET process was forbidden and the fluorescence of the solution was recovered, the detection system is in "on" state. The limit of detection of probe S1 for CNwas 0.2μM, other anions including F-, Cl-, Br-, I-, SO42- AcO-,SCN-, NO3-, NO2-, C1O4-, N3- has no significant interference on the detection of CN".2. A ratio-metric fluorescent probe (S2) for Hg2+ based on FRET mechanism was designed and synthesized, which introduced coumarin as an energy donor and rhodamine B as an energy acceptor, and the two parts are connected by m-phenylenediamine. Before the adding of Hg2+, the spiro ring of Rhodamine B was closed and it can’t accept the energy from the donor, so the solution of S2 has a blue fluorescence. When Hg2+ was added into the solution of S2, the desulfurization of Hg2+ induced the spiro ring of rhodamine B opening and formed oxadiazole, in this case, the donor transfered its energy to the acceptor by FRET, and the fluorescence of the detection system changed from blue to red. Probe S2 showed high selectivity toward Hg2+ and the limit of detection was 3.2 nM. More importantly, probe S2 can be used to detect Hg2+ in living cells.3. Two fluorescent probes for Pd2+ have been developed. We designed and synthesized a rhodamine-based reversible fluorescent probe (S3) for Pd2+ through the introduction of sulfur as a ligand atom to rhodamine B. When Pd2+ was added into the solution of S3, it induced the spiro ring of S3 opening and formed a 1:1 complex with S3, the color of the detection system changed from colorless to red complicated with a strong red fluorescence, after the further addition of CN-, the detection system recovered its original colorless and none fluorescence state. Comparative tests showed that the introduction of sulfur atom played a key role in the process for S3 recognizing Pd2+. S3 exhibited high selectivity toward Pd2+ with a detection limit as low as 2.4 nM. More importantly, S3 can be made into molecular device and detect Pd2+ by test paper. Then we developed a fluorescent probe (S4) based on ICT for Pd2+ by introducing oxime-ether structure to coumarin, the probe can work in pure water and actual water samples, and it can be applied to detect Pd2+ in living cells by fluorescence imaging. |
PDF Full Text Request