Cidlina Antonin, Miletin Miroslav, Fathi-Rasekh Mahtab, Nemykin Victor N, Zimcik Petr, Novakova Veronika
Department of Pharmaceutical Chemistry and Pharmaceutical Analysis, Faculty of Pharmacy in Hradec Kralove, Charles University in Prague, Heyrovskeho 1203, Hradec Kralove, 500 05, Czech Republic.
Department of Chemistry and Biochemistry, University of Minnesota, Duluth, 1039 University Drive, Duluth, MN, 55812, USA.
Chemistry. 2017 Feb 3;23(8):1795-1804. doi: 10.1002/chem.201604978. Epub 2016 Dec 20.
A unique combination of two independent mechanisms of fluorescence quenching, namely intramolecular charge transfer (ICT) from a peripheral donor and protonation of azomethine nitrogen atoms in zinc tetrapyrazinoporphyrazines (TPyzPz), provides a new possibility for sensing pH in a specific range. The pH selectivity was controlled by the different basicities of the donor for ICT (dimethylaminoaryl), which was connected to the macrocycle by π-extended linkers of different lengths. ICT and protonation have been studied in detail by photophysical, spectral (UV/Vis and MCD spectra), and electrochemical measurements, and further supported by theoretical calculations (DFT, TDDFT). The pH-sensing properties of the TPyzPzs have been investigated in THF and in water after anchoring the TPyzPzs to liposomes. The salient pK values were around 1.3 (azomethine nitrogen) and 2.29-4.76 (donor for ICT). The lead indicators (sensing over a pH range of 1.0-2.5) with fairly steep sensing profiles exhibited increases in fluorescence between the OFF/ON states of more than 20-fold and strong absorption in the red region (Q-band maximum >650 nm, ϵ≈2×10 m cm ).
荧光猝灭的两种独立机制的独特组合，即来自外围供体的分子内电荷转移（ICT）和四吡嗪并卟啉锌（TPyzPz）中偶氮甲碱氮原子的质子化，为在特定范围内检测pH值提供了新的可能性。pH选择性由用于ICT的供体（二甲基氨基芳基）的不同碱度控制，该供体通过不同长度的π-扩展连接子与大环相连。通过光物理、光谱（紫外/可见光谱和磁圆二色光谱）和电化学测量对ICT和质子化进行了详细研究，并得到理论计算（密度泛函理论、含时密度泛函理论）的进一步支持。在将TPyzPz锚定到脂质体后，研究了TPyzPz在四氢呋喃和水中的pH传感特性。显著的pK值约为1.3（偶氮甲碱氮）和2.29 - 4.76（用于ICT的供体）。具有相当陡峭传感曲线的领先指示剂（在1.0 - 2.5的pH范围内传感）在关闭/开启状态之间的荧光增加超过20倍，并且在红色区域有强烈吸收（Q带最大值>650 nm，ϵ≈2×10 m cm ）。
