Bulk Inclusions of Double Pyridazine Molecular Rotors in Hexagonal Tris( o-phenylene)cyclotriphosphazene.

A new generation of double pyridazine molecular rotors differing in intramolecular dipole-dipole spacing was synthesized. All rotor molecules formed bulk inclusions in a tris( o-phenylenedioxy)cyclotriphosphazene (TPP) host. Results of dielectric spectroscopy were fitted to a pair of nine-state models that accounted for interactions of neighboring dipoles at either an aligned or opposed possible orientation of the local threefold dipole rotation potentials within a channel of the TPP host. The results indicate dipole-dipole interaction strengths at the 100 to 200 K scale that lead dipoles to preferentially populate a subset of low-energy configurations. They also reveal that pyridazines with ethynyl substituents in 3- and 6-positions have slightly higher rotational barriers (3.2-3.5 kcal/mol) than those carrying one ethynyl and one tert-butyl group (1.9-3.0 kcal/mol). Upon cooling, these barriers reduce the rate of thermal transitions between the potential wells so much that the inclusions cannot achieve ordered dipolar ground states.

Strong Loophole-Free Test of Local Realism.

We present a loophole-free violation of local realism using entangled photon pairs. We ensure that all relevant events in our Bell test are spacelike separated by placing the parties far enough apart and by using fast random number generators and high-speed polarization measurements. A high-quality polarization-entangled source of photons, combined with high-efficiency, low-noise, single-photon detectors, allows us to make measurements without requiring any fair-sampling assumptions. Using a hypothesis test, we compute p values as small as 5.9×10^{-9} for our Bell violation while maintaining the spacelike separation of our events. We estimate the degree to which a local realistic system could predict our measurement choices. Accounting for this predictability, our smallest adjusted p value is 2.3×10^{-7}. We therefore reject the hypothesis that local realism governs our experiment.

Porphene and porphite as porphyrin analogs of graphene and graphite.

Two-dimensional materials have unusual properties and promise applications in nanoelectronics, spintronics, photonics, (electro)catalysis, separations, and elsewhere. Most are inorganic and their properties are difficult to tune. Here we report the preparation of Zn porphene, a member of the previously only hypothetical organic metalloporphene family. Similar to graphene, these also are fully conjugated two-dimensional polymers, but are composed of fused metalloporphyrin rings. Zn porphene is synthesized on water surface by two-dimensional oxidative polymerization of a Langmuir layer of Zn porphyrin with K2IrCl6, reminiscent of known one-dimensional polymerization of pyrroles. It is transferable to other substrates and bridges µm-sized pits. Contrary to previous theoretical predictions of metallic conductivity, it is a p-type semiconductor due to a predicted Peierls distortion of its unit cell from square to rectangular, analogous to the appearance of bond-length alternation in antiaromatic molecules. The observed reversible insertion of various metal ions, possibly carrying a fifth or sixth ligand, promises tunability and even patterning of circuits on an atomic canvas without removing any π centers from conjugation.