Three luminescent polymorphs based on a new copper(I) complex Cu(2-QBO)(PPh3)PF6 (1, PPh3 = triphenylphosphine, 2-QBO = 2-(2'-quinolyl)benzoxazole) have been synthesized and characterized by FT-IR, UV-vis, elemental analyses, and single-crystal X-ray diffraction analyses. Each polymorph can reversibly convert from one to another through appropriate procedures. Interestingly, such interconversion can be distinguished by their intrinsic crystal morphologies and colors (namely α, dark yellow plate, β, orange block, γ, light yellow needle) as well as photoluminescent (PL) properties. X-ray crystal structure analyses of these three polymorphs show three different supramolecular structures from 1D to 3D, which are expected to be responsible for the formation of three different crystal morphologies such as needle, plate, and block. Combination of the experimental data with DFT calculations on these three polymorphs reveals that the polymorphic interconversion is triggered by the conformation isomerization of the 2-QBO ligand and can be successfully controlled by the polarity of the process solvents (affecting the molecular dipole moment) and thermodynamics (affecting the molecular total energy). It is also found that the different crystal colors of polymorphs and their PL properties are derived from different θ values (dihedral angle between benzoxazolyl and quinolyl group of the 2-QBO ligand) and P-Cu-P angles based on TD-DFT calculations. Moreover, an interesting phase interconversion between γ and β has also been found under different temperature, and this result is consistent with the DFT calculations in which the total energy of β is larger than that of γ. This polymorphism provides a good model to study the relationship between the structure and the physical properties in luminescent copper(I) complexes as well as some profound insights into their PL properties.

BackgroundFragile X syndrome (FXS) is the leading inherited cause of autism spectrum disorder, but there remains debate regarding the clinical presentation of social deficits in FXS. The aim of this study was to compare individuals with FXS to typically developing controls (TDC) and individuals with idiopathic autism spectrum disorder (ASD) across two social eye tracking paradigms.MethodsIndividuals with FXS and age- and gender-matched TDC and individuals with idiopathic ASD completed emotional face and social preference eye tracking tasks to evaluate gaze aversion and social interest, respectively. Participants completed a battery of cognitive testing and caregiver-reported measures for neurobehavioral characterization.ResultsIndividuals with FXS exhibited reduced eye and increased mouth gaze to emotional faces compared to TDC. Gaze aversive findings were found to correlate with measures of anxiety, social communication deficits, and behavioral problems. In the social interest task, while individuals with idiopathic ASD showed significantly less social preference, individuals with FXS displayed social preference similar to TDC.ConclusionsThese findings suggest fragile X syndrome social deficits center on social anxiety without the prominent reduction in social interest associated with autism spectrum disorder. Specifically designed eye tracking techniques clarify the nature of social deficits in fragile X syndrome and may have applications to improve phenotyping and evaluate interventions targeting social functioning impairments.

This paper presents new NMR constraints on the conformation of the headgroup, glycerol backbone, and sn-2 chain of 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) in the liquid-crystalline bilayer. Using two-dimensional 13C-1H chemical shift correlation spectroscopy, we find significant dipolar couplings between the carboxyl carbon CO2 and the headgroup protons. This indicates that a conformation in which the DMPC headgroup and the beginning of the sn-2 chain bend toward each other is significantly populated in the fluid bilayer. The predominance of this headgroup orientation can be further confirmed by 31P-13C dipolar couplings from the literature, which constrain the glycerol G2-G3 torsion angle to be close to trans, excluding a significant presence of one of the two conformations found in the DMPC crystal. Combining and reexamining 20 known NMR couplings for the glycerol backbone and its adjacent segments of L alpha-DMPC, we find that several torsion angles and bond orientations in the core of the DMPC molecule are constrained severely and must differ from those in the crystal structure. We propose a consistent molecular model for phosphocholine lipids in the liquid-crystalline phase, with a rigid backbone in the core of the molecule, a bent-back headgroup, and increasing mobility toward the ends of the acyl chains and the headgroup.