Redetermination of {2-[3-(dimethyl­ammonio)propyl­imino­meth­yl]phenol­ato}­dithio­cyanato­zinc(II)

In comparison with the previous refinement of the title complex, [Zn(NCS)2(C12H18N2O)], the present redetermination reveals a different location of the non-carbon attached H atom. Whereas in the previous refinement this H atom was modelled as part of a phenol OH group, the present study indicates a zwitterionic Schiff base ligand with a deprotonated OH group and a protonated tertiary amine group. The Zn(II) atom is four-coordinated by one O and one imine N atoms of the 2-[3-(dimethyl­ammonio)propyl­imino­meth­yl]phenolate Schiff base ligand, and by two N atoms from two thio­cyanate ligands, forming a distorted tetra­hedral geometry. In the crystal structure, adjacent mol­ecules are linked through inter­molecular N—H⋯O hydrogen bonds, forming a chain in the [101] direction

Scene Graph Generation with External Knowledge and Image Reconstruction

Scene graph generation has received growing attention with the advancements in image understanding tasks such as object detection, attributes and relationship prediction,~\etc. However, existing datasets are biased in terms of object and relationship labels, or often come with noisy and missing annotations, which makes the development of a reliable scene graph prediction model very challenging. In this paper, we propose a novel scene graph generation algorithm with external knowledge and image reconstruction loss to overcome these dataset issues. In particular, we extract commonsense knowledge from the external knowledge base to refine object and phrase features for improving generalizability in scene graph generation. To address the bias of noisy object annotations, we introduce an auxiliary image reconstruction path to regularize the scene graph generation network. Extensive experiments show that our framework can generate better scene graphs, achieving the state-of-the-art performance on two benchmark datasets: Visual Relationship Detection and Visual Genome datasets.Comment: 10 pages, 5 figures, Accepted in CVPR 201

Strength of π-Stacking, from Neutral to Cation: Precision Measurement of Binding Energies in an Isolated π-Stacked Dimer

π-Stacking interactions are ubiquitious across chemistry and biochemistry, impacting areas from organic materials and photovoltaics to biochemistry and DNA. However, experimental data is lacking regarding the strength of π-stacking forces—an issue not settled even for the simplest model system, the isolated benzene dimer. Here, we use two-color appearance potential measurements to determine the binding energies of the isolated, π-stacked dimer of fluorene (C13H10) in ground, excited, and ionic states. Our measurements provide the first precise values for π-stacking interaction energies in these states, which are key benchmarks for theory. Indeed, theoretical predictions using ab initio and carefully benchmarked DFT methods are in excellent agreement with experiment

The Role of Torsional Dynamics on Hole and Exciton Stabilization in π‐Stacked Assemblies: Design of Rigid Torsionomers of a Cofacial Bifluorene

Exciton and charge delocalization across π‐stacked assemblies is of importance in biological systems and functional polymeric materials. To examine the requirements for exciton and hole stabilization, cofacial bifluorene (F2) torsionomers were designed, synthesized, and characterized: unhindered (model) MeF2, sterically hindered tBuF2, and cyclophane‐like CF2, where fluorenes are locked in a perfect sandwich orientation via two methylene linkers. This set of bichromophores with varied torsional rigidity and orbital overlap shows that exciton stabilization requires a perfect sandwich‐like arrangement, as seen by strong excimeric‐like emission only in CF2 and MeF2. In contrast, hole delocalization is less geometrically restrictive and occurs even in sterically hindered tBuF2, as judged by 160 mV hole stabilization and a near‐IR band in the spectrum of its cation radical. These findings underscore the diverse requirements for charge and energy delocalization across π‐stacked assemblies