Simultaneous Detection of Circularly Polarized Luminescence and Raman Optical Activity in an Organic Molecular Lemniscate.

Circularly polarized luminescence (CPL) and Raman optical activity (ROA) were observed in a single spectroscopic experiment for a purely organic molecule, an event that had so far been limited to lanthanide-based complexes. The present observation was achieved for [16]cycloparaphenylene lemniscate, a double macrocycle constrained by a rigid 9,9'-bicarbazole subunit, which introduces a chirality source and allows the molecule to be resolved into two configurationally stable enantiomers. Distortion of oligophenylene loops in this lemniscular structure produces a large magnetic transition dipole moment while maintaining the π-conjugation-induced enhancement of the Raman signal, causing the appearance of the CPL/ROA couple. A two-photon mechanism is proposed to explain the population of the lowest-energy excited electronic state prior to the simultaneous emission-scattering event.

Lemniscular [16]Cycloparaphenylene: A Radially Conjugated Figure-Eight Aromatic Molecule.

A cycloparaphenylene-based molecular lemniscate (CPPL) was obtained in a short synthesis involving masked p-phenylene equivalents. The strained figure-eight geometry of CPPL is sustained by the incorporated 9,9'-bicarbazole subunit, which also acts as a stereogenic element. The shape of the distorted [16]cycloparaphenylene nanohoop embedded in CPPL is accurately approximated with a Booth lemniscate. The structure of CPPL, investigated using NMR and Raman spectroscopic methods, revealed strain-dependent features, consistent with the variable curvature of the ring. The electronic and optical properties of CPPL combine features more characteristic of smaller cycloparaphenylenes, such as a reduced optical bandgap and red-shifted fluorescence. CPPL was resolved into enantiomers, which are configurationally stable and provide strong chiroptical responses, including circularly polarized luminescence.

Ferrocene-quinoxaline Y-shaped chromophores as fascinating second-order NLO building blocks for long lasting highly active SHG polymeric films.

The first example of a Y-shaped ferrocene quinoxaline derivative with a surprisingly high and stable second harmonic generation (SHG) response in composite polymeric films is reported. The interesting quadratic hyperpolarizability values of different substituted Y-shaped chromophores are also investigated in solution by the EFISH technique.

Monomeric mixed cadmium-2,2'-dipyridylamine complex derived from ferrocenecarboxylic acid: Structural, electrochemical and biological studies.

A mixed Cd(II) complex {[Cd(FcCOO)2(dpyam)(H2O)][Cd(dpyam)2 (H2O)2]·(ClO4)2·CH3OH} (1) (where FcCOO=ferrocenecarboxylic acid and dpyam=2,2'-dipyridylamine), has been synthesized and characterized by FT-IR, (1)H &(13)C NMR, UV-Vis spectroscopy and elemental analysis. The molecular structure of compound 1 has been determined by the single crystal X-ray diffraction technique, which consists of mixed two different cadmium(II) complexes and two uncoordinated perchlorate ions. The crystal packing shows that the compound 1 self-assembled by intermolecular hydrogen bonding via pyridyl N-H⋯O and coordinated water O⋯H-O-H⋯O, to afford the molecule 2D supramolecular network. Compound 1 exhibits high-energy intraligand (π-π(∗)) fluorescence emission. In electrochemical studies of compound 1 shows negative potential compared with ferrocenecarboxylic acid due to formation of coordination complex with Cd ions. The antibacterial study against the distinct bacterial strains show compound 1 has significant activity.