The development of long-lived luminescent nanoparticles for lifetime imaging is of wide interest as luminescence lifetime is environmentally sensitive detection independent of probe concentration. We report novel iridium-coated gold nanoparticles as probes for multiphoton lifetime imaging with characteristic long luminescent lifetimes based on iridium luminescence in the range of hundreds of nanoseconds and a short signal on the scale of picoseconds based on gold allowing multichannel detection. The tailor-made IrC complex forms stable, water-soluble gold nanoparticles (AuNPs) of 13, 25, and 100 nm, bearing 1400, 3200, and 22 000 IrC complexes per AuNP, respectively. The sensitivity of the iridium signal on the environment of the cell is evidenced with an observed variation of lifetimes. Clusters of iridium nanoparticles show lifetimes from 450 to 590 ns while lifetimes of 660 and 740 ns are an average of different points in the cytoplasm and nucleus. Independent luminescence lifetime studies of the nanoparticles in different media and under aggregation conditions postulate that the unusual long lifetimes observed can be attributed to interaction with proteins rather than nanoparticle aggregation. Total internal reflection fluorescence microscopy (TIRF), confocal microscopy studies and 3D luminescence lifetime stacks confirm the presence of bright, nonaggregated nanoparticles inside the cell. Inductively coupled plasma mass spectrometry (ICPMS) analysis further supports the presence of the nanoparticles in cells. The iridium-coated nanoparticles provide new nanoprobes for lifetime detection with dual channel monitoring. The combination of the sensitivity of the iridium signal to the cell environment together with the nanoscaffold to guide delivery offer opportunities for iridium nanoparticles for targeting and tracking in in vivo models.

Versatile and recyclable heterogeneous photocatalysts based on the use of glass wool supported ruthenium complexes and organic dyes.

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Chemical investigation of nonindigenous Tubastraea coccinea and T. tagusensis by Raman spectroscopy resulted in the identification of carotenoids and indolic alkaloids. Comparison of Raman data obtained for the in situ and crude extracts has shown the potential of the technique for characterizing samples which are metabolic fingerprints, by means of band analysis. Raman bands at ca. 1520, 1160, and 1005 cm(-1) assigned to ν1(C═C), ν2(C-C), and ρ3(C-CH3) modes were attributed to astaxanthin, and the band at 1665 cm(-1) could be assigned to the ν(C-N), ν(C-O), and ν(C-C) coupled mode of the iminoimidazolinone from aplysinopsin. The antioxidant activity of the crude extracts has also been demonstrated, suggesting a possible role of these classes of compounds in the studied corals.

In the present study a series of N-phenyl-1,10-phenanthroline-2-amine derivatives were obtained by heating 2-chlorophenanthroline with aniline derivatives under solvent free conditions in good to excellent yields. The N-phenyl-1,10-phenanthroline-2-amines were employed as substrates in a copper(ii)-catalyzed C-H amination reaction to give derivatives of the novel heterocyclic system benzo[4,5]imidazo[1,2-a][1,10]phenanthroline. The structure of these compounds was predicted to be helical by DFT calculations and single crystal X-ray diffraction of an example of this system confirmed the non-planar helical structure. The luminescence properties of the parent heterocyclic system were characterized.

The present study details the experimental and theoretical characterization of the photophysical properties of 14 examples of 2‐(phenylamino)‐1,10‐phenanthrolines (1). The absorption spectra of 1 are substituent‐dependent but in a general manner present absorption bands at wavelengths of ~230; ~300; ~335 and a shoulder at ~380 nm. Electron‐donating groups (EDG) and electron‐withdrawing groups (EWG), respectively, result in bathochromic and hypsochromic shifts. Compounds 1 are highly luminescent, in contrast to phenanthroline, and emit in the region between 350 and 500 nm with substituent‐dependent λmax emission. The emission spectra show a redshift for EDG (4‐OMe 62 nm; 4‐Me 19 nm) and a blueshift for EWG (4‐CN 41 nm; 4‐CF3 38 nm) relative to the emission of the unsubstituted parent compound 1a. Plotting the λmaxEM against Hammett σ+ constants gave an excellent linear correlation demonstrating the electron‐deficient nature of the excited state and how the substituents (de)stabilize S1. Theoretical calculations revealed a HOMO‐LUMO π‐π* electronic transition to S1 which in combination with difference (S1–S0) in electron density maps revealed charge‐transfer character. Strongly electron‐withdrawing substituents switch off the charge transfer to give rise to a local excitation.

Biologically active naphthoquinones undergo photochemical induced hydrogen abstraction from biologically relevant substrates via a PCET mechanism.

Dibenzoxanthenes are a class of compounds that have attracted attention due principally to their photochemical and photophysical properties. The absorption spectra of the dibenzo[b, h]xanthene derivatives revealed a blue shift in the absorption spectra on increasing the solvent polarity. The laser flash photolysis technique was used to study the reactivity of the triplet excited states of the dibenzo[b, h]xanthene‐5,6,8,13‐tetrone derivatives. Hydrogen atom or electron donors, including model biological compounds, led to quenching of the excited state and formation of a new transient, thus revealing type I photosensitizer reactivity. Further, energy transfer to oxygen to generate singlet oxygen was also observed demonstrating type II photosensitization. Additionally, the novel dibenzo[b, h]xanthene‐5,6,8,13‐tetrol acetates revealed fluorescence emission with maximum wavelengths between 350–360 nm.