The third-order nonlinear optical properties of a series of resonance benzo[a]phenoxazinium salts in acetic acid solution were studied using the Z-scan technique employing a Nd:YAG nanosecond laser at 532 nm. The compounds displayed strong reverse absorption with third-order nonlinear optical coefficients of 0.42–1.20 × 10−11 esu and second hyperpolarizabilities of 2.75–7.29 × 10−29 esu, respectively. Quantum chemical calculations showed that the compound with more stable highest occupied molecular orbital energy also displayed highest second hyperpolarizability.

A series of phenothiazinium chlorides, which have good solubility in polar solvents and good thermal stability, were evaluated in dimethyl sulfoxide solution for third-order nonlinear optical properties at 532 nm using a nanosecond and picosecond Z-scan technique. The title compounds exhibit strong reverse saturable absorption and nonlinear refraction. The third-order nonlinear optical properties were obtained under irradiation with either a nanosecond or picosecond laser. The nonlinear mechanism is revealed as excited-state nonlinearity by a picosecond pump-probe response experiment for one of the compounds. The absorption and emission maxima, Stokes shift and quantum yield are also reported.

Tropical diseases are serious infectious diseases caused by protozoan parasites in tropical and subtropical regions. Novel, effective, safe, and inexpensive drugs are required to treat the parasites and contribute to the global goal of eradication. A series of phenothiazinium chlorides were synthesized and evaluated for in vitro activities against Plasmodium falciparum, Trypanosoma cruzi, Trypanosoma brucei rhodesiense, and Leishmania donovani. Notably, 3,7-bis(piperidinyl)phenothiazinium chloride showed IC50 of 0.097 μmol L−1 against T. cruzi and 3,7-bis(benzyl(methyl)amino)phenothiazinium chloride exhibited IC50 of 0.081 μmol L−1 against L. donovani, although the cytotoxicities of these compounds against L-6 cells were observed at low concentration.

A selective, sensitive probe for Hg(II) ions, 7-(diethylamino)-3-methyl-2H-benzo[b][1,4] oxazine-2-thione (1), is developed. Compound 1 behaves as a ratiometric probe, exhibiting a large blue shift of 100 nm in its absorption spectra upon exposure to Hg(II) ions. The dramatic color change of the solution made ‘naked-eye’ detection of Hg(II) ions possible. Emission spectra of 1 displayed a selective enhancement in intensity in the presence of Hg(II) ions. ESI+-MS analysis indicated that Hg2+-induced desulfurization caused the large absorption response.

A ratiometric, near-infrared, and fully water-soluble probe, a phenoxazinium-based chemosensor bearing an anilino thiaazacrown, was successfully synthesized and characterized. The use of this probe for the selective ratiometric detection of Hg2+ in pure water is reported. The probe shows good selectivity for Hg2+, and a large blue shift (75 nm) of the complex’s absorption maximum was observed.

In this paper a polymethacrylate with pendent azobenzothiazole (pBAMA) was synthesized via free radical polymerization, and the polymer exhibited good solubility and thermal stability. Films of pBAMA sandwiched between bottom indium−tin oxide (ITO) or Pt electrode and top Al electrodes show the excellent FLASH memory behaviors or write once read many times (WORM) behaviors according to the film thickness. Particularly, the charge transport processes during the OFF to ON states were precisely discussed to reveal the physical mechanism which is still a topic of active debate in any given device structure. One metal islands layer was confirmed lying in the pBAMA films, and this layer decided the memory characteristics of different device structures. The fabricated devices show the excellent memory characteristics as the highest ON/OFF ratio up to 107, and enduring 108 read cycles under −1 V pulse voltages, these properties promised that the memory device based on pBAMA has a potential application for the future advanced computers and digital electronics.