Reported here is a new hybrid macrocycle, cyclo[1]furan[1]pyridine[4]pyrrole (1), that bears analogy to the previously reported mixed heterocycle system cyclo[2]pyridine[4]pyrrole (2) and cyclo[6]pyrrole 3, an all-pyrrole 22 π-electron aromatic expanded porphyrin. The oxidized, dianionic form of 1, [1 - 4H](2-), has been characterized as its uranyl complex. In contrast to 2 and 3 and in spite of the presence of a 2,6-disubstituted pyridine subunit, the uranyl complex of [1 - 4H](2-) displays solid-state structural and solution-phase spectroscopic features consistent with contributions to the overall electronic structure that involve a conjugated, (4n + 2) π-electron aromatic periphery.

We report herein a new ditopic calix[4]arene receptor 25,27-bis-{[4-amino-4-(1-naphthyl)-2-oxo-3-butenyl]oxy}-26,28-dihydroxycalix[4]arene (2) for the simultaneous complexation of anionic and cationic species. The host molecule 25,27-bis{[3-(1-naphthyl)-5-isoxazolyl]methoxy}-26,28-dihydroxycalix[4]arene (1) was synthesised first and was followed by a [Mo(CO)6]-mediated ring-opening reaction to give the target receptor 2. The binding properties of ligands 1 and 2 towards metal ions in CH3CN were investigated by UV/Vis and fluorescence spectroscopies. The results showed that both ligands 1 and 2 were highly selective for Cu(II) ions. Upon titration with Cu(II), the fluorescence of 1 was severely quenched, whereas 2 showed strong fluorescence enhancement because the metal ions help to lock the conformation of the fluorophores. During the complexation of 2 with Cu(II), the Cu(II) was reduced to Cu(I) by the free phenolic OH of 2, whereas the phenol was oxidised by Cu(II), after which it assisted in the trapping of Cu(I). Ditopic behaviour was observed for the complex 2.Cu(I), which showed further enhancement of its fluorescence intensity upon complexation with anions such as acetate or fluoride.

When a sample being tested is optically opaque or has a high absorption coefficient, a reflective measurement is often more suitable than a transmission measurement. We report the design and evaluation of a reflective terahertz time-domain spectroscopy (R-THz-TDS), using air as THz wave emitter and sensor, together with air-biased-coherent-detection (ABCD) method for the first time. With an 85 fs pulse amplified laser, we demonstrate a usable bandwidth from 0.5 THz to 12 THz, together with a peak dynamic range (DR) better than 2000:1 and a peak THz electrical field greater than 30 kV/cm. With a 32 fs pulse amplified laser, the usable bandwidth is remarkably expanded to a continuous 35 THz. Several far-infrared optical properties in various samples are reported. Furthermore, the time-resolved optical pump-THz probe experiment is performed. Finally, the uniqueness and advantage of this spectrometer are comprehensively compared with traditional THz-TDS and Fourier transform infrared (FTIR) spectroscopy.

Chemical tools that can report radioactive isotopes would be of interest to the defense community. Here we report ~250 nm polymeric nanoparticles containing porphyrinoid macrocycles with and without pre-complexed depleted uranium and demonstrate that the latter species may be detected easily and with high sensitivity via photoacoustic imaging. The porphyrinoid macrocycles used in the present study are non-aromatic in the absence of the uranyl cation, but aromatic after cation complexation. We solubilized both the freebase and metalated forms of the macrocycles in poly(lactic-co-glycolic acid) and found a peak in photoacoustic signal at 910 nm excitation in the case of the uranyl complex. The signal was stable for at least 15 minutes and allowed detection of uranium concentrations down to 6.2 ppb (5.7 nM) in vitro and 0.57 ppm (19 fCi; 0.52 μM) in vivo. To the best of our knowledge, this is the first report of a nanoparticle that detects an actinide cation via photoacoustic imaging.