Determination of Controlled Self-Assembly of a Paracrystalline Material by Homology Modelling with Hybrid NMR and TEM.

Controlling complexity, flexibility, and functionality of synthetic and biomimetic materials requires insight into how molecular functionalities can be exploited for steering their packing. A fused NDI-salphen (NDI=naphthalene diimide) prototypic artificial photosynthesis material, DATZnS, is shown to be comprised of a phenazine motif, in which the alignment of electric dipole moments in a P2/c supramolecular scaffold can be modulated with bulky substituents. They can also be switched between parallel stacks of dipoles running antiparallel in the DATZnS-H compared with parallel stacks of dipoles in polar layers running in opposite directions in the DATZnS(3'-NMe) parent compound.

A quantitative analysis of light-driven charge transfer processes using voronoi partitioning of time dependent DFT-derived electron densities.

An analytical method is presented that provides quantitative insight into light-driven electron density rearrangement using the output of standard time-dependent density functional theory (TD-DFT) computations on molecular compounds. Using final and initial electron densities for photochemical processes, the subtraction of summed electron density in each atom-centered Voronoi polyhedron yields the electronic charge difference, Q . This subtractive method can also be used with Bader, Mulliken and Hirshfeld charges.

Probing Zeolite Crystal Architecture and Structural Imperfections using Differently Sized Fluorescent Organic Probe Molecules.

A micro-spectroscopic method has been developed to probe the accessibility of zeolite crystals using a series of fluorescent 4-(4-diethylaminostyryl)-1-methylpyridinium iodide (DAMPI) probes of increasing molecular size. Staining large zeolite crystals with MFI (ZSM-5) topology and subsequent mapping of the resulting fluorescence using confocal fluorescence microscopy reveal differences in structural integrity: the 90° intergrowth sections of MFI crystals are prone to develop structural imperfections, which act as entrance routes for the probes into the zeolite crystal. Polarization-dependent measurements provide evidence for the probe molecule's alignment within the MFI zeolite pore system.

A Hybrid Solid-State NMR and Electron Microscopy Structure-Determination Protocol for Engineering Advanced para-Crystalline Optical Materials.

Hybrid magic-angle spinning (MAS) NMR spectroscopy and TEM were demonstrated for de novo structure determination of para-crystalline materials with a bioinspired fused naphthalene diimide (NDI)-salphen-phenazine prototype light-harvesting compound. Starting from chiral building blocks with C molecular symmetry, the asymmetric unit was determined by MAS NMR spectroscopy, index low-resolution TEM diffraction data, and resolve reflection conditions, and for the first time the ability to determine the space group from reciprocal space data using this hybrid approach was shown. Transfer of molecular C symmetry into P2/c packing symmetry provided a connection across length scales to overcome both lack of long-range order and missing diffraction-phase information.

Characteristic Contrast in Δfmin Maps of Organic Molecules Using Atomic Force Microscopy.

Scanning tunneling microscopy and atomic force microscopy can provide detailed information about the geometric and electronic structure of molecules with submolecular spatial resolution. However, an essential capability to realize the full potential of these techniques for chemical applications is missing from the scanning probe toolbox: chemical recognition of organic molecules. Here, we show that maps of the minima of frequency shift-distance curves extracted from 3D data cubes contain characteristic contrast.

Synthesis and photophysics of a red-light absorbing supramolecular chromophore system.

In search of supramolecular antenna systems for light-harvesting applications, we report on a short and effective synthesis of a fused NDI-zinc-salphen-based chromophore (salphen = bis-salicylimide phenylene) and its photophysical properties. A supramolecular recognition motif is embedded into the chromophoric π-system of this compound. The fused π-chromophore behaves as one pigment, absorbs light between 600 and 750 nm and displays a modest Stokes shift.