Formation of Planar π-Conjugated Sheets in Cocrystals of Bis(iodoethynyl)pyridines and Bipyrimidylalkynes: Cooperative C-H···N Hydrogen Bonds and sp-C-I···N Halogen Bonds.

The cocrystallization of the ditopic halogen bond donors 2,5-, 2,6-, 3,5-bis(iodoethynyl)pyridines with the dipyrimidyls 1,2-bis(5-pyrimidyl)ethyne and 1,4-bis(5-pyrimidyl)butadiyne is explored. The cocrystal components have complementary shapes and functional groups so that the noncovalent C-I···N halogen bonding and C-H···N hydrogen bonding interactions are complementary resulting in 1:1 cocrystals with the ditopic halogen bond accepting bipyrimidyls. The cocrystals feature π-stacked planar sheets of alternating bis(iodoalkynes) and bipyrimidyls held together in one direction by I···N halogen bonds and in the roughly orthogonal direction by pyridine-pyridine and pyrimidine-pyrimidine C-H···N hydrogen bonds.

Role of secondary interactions in a series of 2:1 halogen-bonded cocrystals formed between 4-(dimethylamino)pyridine and ditopic halogen-bond donors.

The structures of a series of 2:1 cocrystals formed between 4-(dimethylamino)pyridine and each of 1,2,4,5-tetrachloro-3,6-diiodobenzene, 2CHN·CClI, 1,2,4,5-tetrabromo-3,6-diiodobenzene, 2CHN·CBrI, 1-bromo-4-iodo-2,3,5,6-tetrafluorobenzene, 2CHN·CBrFI, and 1,2-dibromo-4,5-difluoro-3,6-diiodobenzene, 2CHN·CBrFI, are reported. In all five structures, the core halogen-bonded 2:1 trimolecular units have geometrically similar parameters, with the central halogen-bond donor flanked by two pyridine halogen-bond acceptors twisted with respect to the central halogen-bond donor at angles ranging from 76 to 86°. The I.

Halogen-Bonded Supramolecular Parallelograms: From Self-Complementary Iodoalkyne Halogen-Bonded Dimers to 1:1 and 2:2 Iodoalkyne Halogen-Bonded Cocrystals.

The formation of supramolecular parallelograms utilizing iodoalkyne-pyridine halogen bonding is described. The crystal structures of four iodoalkynyl-substituted (phenylethynyl)pyridines demonstrate the feasibility of discrete self-complementary dimer formation. These compounds 3-(2-iodoethynyl-phenylethynyl) pyridine (), 2-(3-iodoethynyl-phenylethynyl) pyridine (), 3-(4,5-difluoro-2-iodoethynyl-phenylethynyl) pyridine (), and 2-(5-iodoethynyl-2,4-dimethylphenylethynyl) pyridine () all form parallelogram-shaped dimers with two self-complementary short N-I halogen bonds.

Differential phase contrast (DPC) mapping electric fields: Optimising experimental conditions.

DPC in Scanning Transmission Electron Microscopy (STEM) is a valuable method for mapping the electric fields in semiconductor materials. However, optimising the experimental conditions can be challenging. In this paper, we test and compare critical experimental parameters, including the convergence angle, camera length, acceleration voltage, sample configuration, and orientation using a four-quadrant segmented detector and a Si specimen containing layers of different As concentrations.

Co-crystal sustained by π-type halogen-bonding inter-actions between 1,4-di-iodo-perchloro-benzene and naphthalene.

The formation and crystal structure of a co-crystal based upon 1,4-di-iodo-perchloro-benzene (CICl) as the halogen-bond donor along with naphthalene (nap) as the acceptor is reported. The co-crystal [systematic name: 1,2,4,5-tetra-chloro-3,6-di-iodo-benzene-naphthalene, (CICl)·(nap)] generates a chevron-like structure that is held together primarily by π-type halogen bonds (. C-I⋯π contacts) between the components.

Rapid Access to Encapsulated Molecular Rotors via Coordination-Driven Macrocycle Formation.

Macrocycle formation that relies upon trans metal coordination of appropriately placed pyridine ligands within an arylene ethynylene construct provides rapid and reliable access to molecular rotators encapsulated within macrocyclic stators. Showing no significant close contacts to the central rotators, X-ray crystallography of Ag -coordinated macrocycles provides plausibility for unobstructed rotation or wobbling of rotators within the central cavity. Solid-state C NMR of Pd -coordinated macrocycles supports the notion of unobstructed movement of simple arenes in the crystal lattice.

π-Complexation and C-H hydrogen bonding in the formation of colored cocrystals.

The present study evaluates the potential combination of charge-transfer electron-donor-acceptor π-π complexation and C-H hydrogen bonding to form colored cocrystals. The crystal structures of the red 1:1 cocrystals formed from the isomeric pyridines 4- and 3-{2-[4-(dimethylamino)phenyl]ethynyl}pyridine with 1-[2-(3,5-dinitrophenyl)ethynyl]-2,3,5,6-tetrafluorobenzene, both CHFNO·CHN, are reported. Intermolecular interaction energy calculations confirm that π-stacking interactions dominate the intermolecular interactions within each crystal structure.

Halogen-bonded co-crystal containing 1,3-di-iodo-perchloro-benzene and the photoproduct -tetra-kis-(pyridin-4-yl)cyclo-butane resulting in a zigzag topology.

The formation and crystal structure of a zigzag network held together by I⋯N halogen bonds is reported. In particular, the halogen-bond donor is 1,3-di-iodo-perchloro-benzene ( ) while the acceptor is the photoproduct -tetra-kis-(pyridin-4-yl)cyclo-butane (). Curiously, within the resulting co-crystal ( )·(), the photoproduct accepts only two halogen bonds between neighbouring 4-pyridyl rings and as a result behaves as a bent two-connected node rather than the expected four-connected centre.

5-{[4-(Di-methyl-amino)-phen-yl]ethyn-yl}pyrimidine-1,2,3,5-tetra-fluoro-4,6-di-iodo-benzene (1/2).

The treatment of 5-{[4-(di-methyl-amino)-phen-yl]ethyn-yl}pyrimidine with a threefold excess of 1,2,3,5-tetra-fluoro-4,6-di-iodo-benzene in di-chloro-methane solution led to the formation of the unexpected 1:2 title co-crystal, CHN·2CFI. In the extended structure, two unique C-I⋯N halogen bonds from one of the 1,2,3,5-tetra-fluoro-4,6-di-iodo-benzene mol-ecules to the pyrimidine N atoms of the 5-{[4-(di-methyl-amino)-phen-yl]ethyn-yl}pyrimidine mol-ecule generate [110] chains and layers of these chains are π-stacked along the axis direction. The second 1,2,3,5-tetra-fluoro-4,6-di-iodo-benzene mol-ecule resides in channels formed parallel to the -axis direction between stacks of 5-{[4-(di-methyl-amino)-phen-yl]ethyn-yl}pyrimidine mol-ecules and inter-acts with them C-I⋯π(alkyne) contacts.

A structural and computational comparison of close contacts and related intermolecular energies of interaction in the structures of 1,3-diiodo-5-nitrobenzene, 1,3-dibromo-5-nitrobenzene, and 1,3-dichloro-5-nitrobenzene.

1,3-Diiodo-5-nitrobenzene, CHINO, and 1,3-dibromo-5-nitrobenzene, CHBrNO, crystallize in the centrosymmetric space group P2/m, and are isostructural with 1,3-dichloro-5-nitrobenzene, CHClNO, that has been redetermined at 100 K for consistency. While the three-dimensional packing in all three structures is similar, the size of the halogen atom affects the nonbonded close contacts observed between molecules. Thus, the structure of 1,3-diiodo-5-nitrobenzene features a close Type 1 I.

Single-particle cryo-EM structures from iDPC-STEM at near-atomic resolution.

In electron cryomicroscopy (cryo-EM), molecular images of vitrified biological samples are obtained by conventional transmission microscopy (CTEM) using large underfocuses and subsequently computationally combined into a high-resolution three-dimensional structure. Here, we apply scanning transmission electron microscopy (STEM) using the integrated differential phase contrast mode also known as iDPC-STEM to two cryo-EM test specimens, keyhole limpet hemocyanin (KLH) and tobacco mosaic virus (TMV). The micrographs show complete contrast transfer to high resolution and enable the cryo-EM structure determination for KLH at 6.

Atomic imaging of zeolite-confined single molecules by electron microscopy.

Single-molecule imaging with atomic resolution is a notable method to study various molecular behaviours and interactions. Although low-dose electron microscopy has been proved effective in observing small molecules, it has not yet helped us achieve an atomic understanding of the basic physics and chemistry of single molecules in porous materials, such as zeolites. The configurations of small molecules interacting with acid sites determine the wide applications of zeolites in catalysis, adsorption, gas separation and energy storage.

Co-operative halogen bonds and nonconventional sp-C-H...O hydrogen bonds in 1:1 cocrystals formed between diethynylpyridines and N-halosuccinimides.

The rapid evaporation of 1:1 solutions of diethynylpyridines and N-halosuccinimides, that react together to form haloalkynes, led to the isolation of unreacted 1:1 cocrystals of the two components. The 1:1 cocrystal formed between 2,6-diethynylpyridine and N-iodosuccinimide (CHINO·CHN) contains an N-iodosuccinimide-pyridine I..

Halogen-bonded zigzag mol-ecular network based upon 1,2-di-iodo-perchloro-benzene and the photoproduct -1,3-bis-(pyridin-4-yl)-2,4-di-phenyl-cyclo-butane.

The formation and crystal structure of a zigzag mol-ecular network held together by I⋯N halogen bonds is reported. In particular, the halogen-bond donor is 1,2-di-iodo-perchloro-benzene ( ) while the acceptor is a head-to-tail photoproduct, namely -1,3-bis-(pyridin-4-yl)-2,4-di-phenyl-cyclo-butane ( ). In this co-crystal ( )·( ), the donor acts as a bent two-connected node while the acceptor behaves as a linear linker to form the extended solid.

Controlling Thermal Expansion in Supramolecular Halogen-Bonded Mixed Cocrystals through Synthetic Feed and Dynamic Motion.

Control over thermal expansion (TE) behaviors in solid materials is often accomplished by modifying the molecules or intermolecular interactions within the solid. Here, we use a mixed cocrystal approach and incorporate molecules with similar chemical structures, but distinct functionalities. Development of mixed cocrystals is at a nascent stage, and here we describe the first mixed cocrystals sustained by one-dimensional halogen bonds.

Complementary, Cooperative Ditopic Halogen Bonding and Electron Donor-Acceptor π-π Complexation in the Formation of Cocrystals.

This study expands and combines concepts from two of our earlier studies. One study reported the complementary halogen bonding and π-π charge transfer complexation observed between isomeric electron rich 4-,-dimethylaminophenylethynylpyridines and the electron poor halogen bond donor, 1-(3,5-dinitrophenylethynyl)-2,3,5,6-tetrafluoro-4-iodobenzene while the second study elaborated the ditopic halogen bonding of activated pyrimidines. Leveraging our understanding on the combination of these non-covalent interactions, we describe cocrystallization featuring ditopic halogen bonding and π-stacking.

Imaging atomic motion of light elements in 2D materials with 30 kV electron microscopy.

Scanning transmission electron microscopy (STEM) is the most widespread adopted tool for atomic scale characterization of two-dimensional (2D) materials. However, damage free imaging of 2D materials with electrons has remained problematic even with powerful low-voltage 60 kV-microscopes. An additional challenge is the observation of light elements in combination with heavy elements, particularly when recording fast dynamical phenomena.

Conformational control through co-operative nonconventional C-H...N hydrogen bonds.

We report the design, synthesis, and crystal structure of a conjugated aryleneethynyl molecule, 2-(2-{4,5-dimethoxy-2-[2-(2,3,4-trifluorophenyl)ethynyl]phenyl}ethynyl)-6-[2-(pyridin-2-yl)ethynyl]pyridine, CHFNO, that adopts a planar rhombus conformation in the solid state. The molecule crystallizes in the space group P-1, with Z = 2, and features two intramolecular sp-C-H..

The WISHED Randomized Controlled Trial: Impact of an Interactive Health Communication Application on Home Dialysis Use in People With Chronic Kidney Disease.

Background: While home dialysis therapies are more cost effective and may offer improved health-related quality of life, uptake compared to in-center hemodialysis remains low.

Objective: To test whether a web-based interactive health communication application (IHCA) compared to usual care would increase home dialysis use.

Design: Randomized control trial.

Controlling Topology within Halogen-Bonded Networks by Varying the Regiochemistry of the Cyclobutane-Based Nodes.

The formation of a pair of extended networks sustained by halogen bonds based upon two regioisomers of a photoproduct, namely -1,3-bis(4-pyridyl)-2,4-bis(phenyl)cyclobutane (-PP) and -1,2-bis(4-pyridyl)-3,4-bis(phenyl)cyclobutane (-PP), that have varied topology is reported. These networks are held together via I⋯N halogen bonds between the photoproduct and the halogen-bond donor 1,4-diiodoperchlorobenzene (CICl). The observed topology in each solid is controlled by the regiochemical position of the halogen-bond accepting 4-pyridyl group.

Arylethynyl Helices Supported by π-Stacking and Halogen Bonding.

Co-crystallization of a pyridyl-containing arylethynyl (AE) moiety with 1,4-diiodotetrafluorobenzene leads to unique, figure-eight shaped helical motifs within the crystal lattice. A slight twist in the AE backbone allows each AE unit to simultaneously interact with haloarene units that are stacked on top of one another. Left-handed (M) and right-handed (P) helices are interspersed in a regular pattern throughout the crystal.

Crystal structure and photoreactivity of a halogen-bonded cocrystal based upon 1,2-diiodoperchlorobenzene and 1,2-bis(pyridin-4-yl)ethylene.

The formation of a photoreactive cocrystal based upon 1,2-diiodoperchlorobenzene (1,2-CICl) and trans-1,2-bis(pyridin-4-yl)ethylene (BPE) has been achieved. The resulting cocrystal, 2(1,2-CICl)·(BPE) or CClI·0.5CHN, comprises planar sheets of the components held together by the combination of I.

Ditopic halogen bonding with bipyrimidines and activated pyrimidines.

The potential of pyrimidines to serve as ditopic halogen-bond acceptors is explored. The halogen-bonded cocrystals formed from solutions of either 5,5'-bipyrimidine (CHN) or 1,2-bis(pyrimidin-5-yl)ethyne (CHN) and 2 molar equivalents of 1,3-diiodotetrafluorobenzene (CFI) have a 1:1 composition. Each pyrimidine moiety acts as a single halogen-bond acceptor and the bipyrimidines act as ditopic halogen-bond acceptors.

Triple-Pnictogen Bonding as a Tool for Supramolecular Assembly.

Supramolecular assembly utilizing simultaneous formation of three pnictogen bonds around a single antimony vertex was explored via X-ray crystallography, solution NMR, and computational chemistry. An arylethynyl (AE) ligand was designed to complement the three electrophilic regions around the Sb compound. Though solution studies reveal large binding constants for individual pyridyl units with the Sb donor, the rigidity and prearrangement of the AE acceptor proved necessary to achieve simultaneous binding of three acceptors to the Sb-centered pnictogen-bond donor.