Porphodilactones represent the porphyrin analogues, in which the peripheral bonds of two pyrrole rings are replaced by lactone moieties. They provide an opportunity to investigate how β-substituent orientation of porphyrinoids modulates the electronic structures and optical properties, in a manner similar to what is observed with naturally occurring chlorophylls. In this work, a comprehensive description of the synthesis, characterization, and optical properties of meso-tetrakispentafluorophenylporphodilactone isomers is first reported. The β-dilactone moieties are found to lie at opposite pyrrole positions (trans- and cis-configurations are defined by the relative orientations of the carbonyl group when one lactone moiety is fixed), in accordance with earlier computational predictions (Gouterman, M. J. Am. Chem. Soc. 1989, 111, 3702). The relative orientation of the β-dilactone moieties has a significant influence on the electronic structures and photophysical properties. For example, the Qy band of trans-porphodilactone is red-shifted by 19 nm relative to that of the cis-isomer, and there is a 2-fold increase in the absorption intensity, which resembles the similar trends that have been reported for natural chlorophyll f and d. An in depth analysis of magnetic circular dichroism spectral data and TD-DFT calculations at the B3LYP/6-31G(d) level of theory demonstrates that the trans- and cis-orientations of the dilactone moieties have a significant effect on the relative energies of the frontier π-molecular orbitals. Importantly, the biological behaviors of the isomers reveal their different photocytotoxicity in NIR region (>650 nm). The influence of the relative orientation of the β-substituents on the optical properties in this context provides new insights into the electronic structures of porphyrinoids which could prove useful during the development of near-infrared absorbing photosensitizers.

We have performed a detailed investigation of the molecular beam epitaxial growth and characterization of InN nanowires spontaneously formed on Si(111) substrates under nitrogen rich conditions. By employing an in situ deposited thin (approximately 0.5 nm) In seeding layer prior to growth initiation, we have achieved, for the first time, non-tapered epitaxial InN nanowires, which exhibit record narrow spectral linewidths of 14 and 40 meV at 5 K and 300 K, respectively. Detailed studies confirm that the wires are nearly free of dislocations and stacking faults. The achievement of non-tapered, nearly homogeneous InN nanowires also enables, for the first time, the derivation of the band gap of InN directly from PL spectroscopy in the temperature range of 5-300 K.

The ability to modulate the spin states of adsorbed molecules is in high demand for molecular spintronics applications. Here, we demonstrate that the spin state of a corrole complex can be tuned by expanding its fused ring as a result of the modification to the d–π interaction between the metal and ligand. A bicyclo[2.2.2]octadiene-fused copper corrole can readily be converted into a tetrabenzocorrole radical on an Au(111) substrate during the sublimation process. In the scanning tunnelling spectroscopy spectrum, a sharp Kondo resonance appears near the Fermi level on the corrole ligand of the tetrabenzocorrole molecule. In contrast, a non-fused-ring-expanded copper corrole molecule, copper 5,10,15-triphenylcorrole, shows no such Kondo feature. Mapping of the Kondo resonance demonstrates that the spin distribution of the tetrabenzocorrole molecule can be further modified by the rotation of the meso-aryl groups, in a manner that could lead to applications in molecular spintronics.

In this paper, the achievement of nearly intrinsic InN nanowire is reported. With the use of an in situ deposited In seeding layer, nearly defect‐free, non‐tapered InN nanowires are grown directly on Si(111) substrates by molecular beam epitaxy. The photoluminescence emission of a single InN nanowire is analyzed, which exhibits, for the first time, a very narrow (∼13 meV) spectral linewidth, a clear band filling effect with the increase of excitation power, and a significant red shift of the peak energy with increasing temperature. Detailed analysis confirms the InN nanowire has a very low residual doping of ∼1 × 1016 cm−3, or less. It is further suggested that there is a small, or negligible level of electron accumulation at the lateral nonpolar surfaces of nearly intrinsic InN nanowires, which is in direct contrast to the commonly observed surface electron accumulation of n‐type degenerate InN.