57005-60-4Relevant articles and documents
OFF-ON-OFF Red-Emitting Fluorescent Indicators for a Narrow pH Window
Cidlina, Antonin,Miletin, Miroslav,Fathi-Rasekh, Mahtab,Nemykin, Victor N.,Zimcik, Petr,Novakova, Veronika
, p. 1795 - 1804 (2017)
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 pKavalues 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, ?≈2×106m?1cm?1).
Structure-activity Relationship of Herbicidal 2,3-Dicyano-5-Substituted Pyrazines
Nakamura, Akira,Ataka, Toshiei,Segawa, Hirozo,Takeuchi, Yasutomo,Takematsu, Tetsuo
, p. 1555 - 1560 (2007/10/02)
Sixty six 2,3-dicyano-5-substituted pyrazines were synthesized and their herbicidal activities against barnyard grass were measured in pot tests to clarify the relationship between chemical structure and activity.The activity of 59 derivatives was related parabolically to the hydrophobic substituent parameter at the 5-position of the pyrazine ring.
