Triple pnictogen bonding refers to the ability of a pnictogen atom to engage in three simultaneous pnictogen bonds (PnBs) to a complementary partner through a single pnictogen atom. This ...supramolecular strategy was recently introduced as a unique facet of pnictogen bonding as compared to other named supramolecular interactions. Here, the ability of bismuth to participate in this phenomenon is demonstrated using Bi((NC9H7)3CH3). The study reveals that Bi engages in stronger PnBs than the analogous Sb system. The results have been contrasted with Bi systems that form strong coordination bonds, and analysis of the electron density along the bond path reveals key differences. The solution behavior of these newly synthesized supramolecules were studied by PFGSE NMR spectroscopy and they are found to remain intact in solution. Molecular design strategies that allow for triple pnictogen bonding should find use in the fields of molecular recognition and crystal engineering.
In the current work, graphene oxide (GO) and sulfonated graphene oxide (SGO) were synthesized and composited with Nafion to increase the water uptake (WUP) and ion exchange capacity (IEC) of the cast ...membranes. Ionic polymer-metal composite (IPMC) soft actuators in protonated form were fabricated based on the cast pure Nafion, Nafion/GO and Nafion/SGO membranes. The effects of incorporating GO and SGO in IPMC actuators were followed using physicochemical, electrochemical and electromechanical measurements and were compared with the corresponding behavior of pure Nafion-based IPMC actuators. Morphology analysis of IPMCs showed effective incorporation of GO and SGO and clarified the dependency of Pt electrode structure on the SGO content of the Nafion membranes. The addition of SGO resulted in dramatic increases in the WUP, IEC and hydrated thickness of the Nafion membranes and also in the capacitance, ionic conduction and in the tip displacement of the IPMC actuators. The small tip displacement of pure Nafion-based actuator was enhanced by eight times by adding 1 wt% SGO. The results suggested that the dispersion of SGO throughout the continuous polymeric matrix significantly reduce water loss by increasing the obstructions within the Nafion membrane and also by formation of denser Pt grains in the electrode regions.
Abstract This work reports the synthesis and self‐assembly of perylene diimide (PDI)‐containing macrocycles designed for facile and high‐throughput production of shape‐persistent, macrocyclic organic ...electronic materials. Specifically, utilizing dynamic covalent chemistry (DCvC), this work showcases ditopic thiols can be utilized as building blocks toward 3D materials with defined porosity, low‐lying unoccupied molecular orbitals, and intrinsic fluorescence. The PDI disulfide‐linked macrocycles are generated in a single step from the thiolic building block to yield dimeric through pentameric assemblies in overall 95% combined yield; moreover, following self‐assembly, the disulfide ensemble is sulfur extruded to the more kinetically stable thioether in 79% combined yield. The modular design suggests these methods can be used to easily self‐assemble other electronically active precursors for utility in porous macrocyclic materials where stepwise pathways may be laborious and/or low yielding.
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. Calculations and X-ray structures suggest that negative cooperativity upon sequential binding of three acceptors to a Sb center limits the utility of triple-pnictogen bonding pyridyl acceptors. These limitations can be negated, however, when positive cooperativity is designed into a complementary acceptor ligand.
Designing materials to have three unique but predictable thermal expansion axes represents a major challenge. Inorganic materials and hybrid frameworks tend to crystallize in high-symmetry space ...groups, which necessarily limits this by affording isotropic behavior. On the other hand, molecular organic materials tend to crystallize in lower-symmetry space groups, offering significant opportunity to achieve anisotropic properties. The challenge arises in self-assembling the organic components into a predictable arrangement to afford predictable thermal expansion properties. Here, we demonstrate a design strategy for engineering organic solid-state materials that exhibit anisotropic thermomechanical behaviors. Presented are a series of multicomponent solids wherein one component features a BODPIY core strategically decorated with orthogonal hydrogen- and halogen-bond donor groups. A series of size-matched halogen-bond acceptors are used as the second component in each solid. By matching the molecular dimensions with the interaction strength, we obtained good control over the anisotropic thermal expansion of the molecular materials. Moreover, using shape-size mimicry and propensity for molecular motion, a rare ternary molecular system that is isostructural to the two binary solids was successfully achieved. The diiodo-functionalized BODIPY core in this study has been previously used in photocatalysts, and halogen bonding was hypothesized as a driving force; here, we provide corroborating solution and solid-state evidence of intermolecular halogen bonding in multicomponent solids featuring a 2,6-diiodo BODIPY.
Improved Synthesis of N‐methyl Cadaverine Anderson, Kayla Nicole; Moaven, Shiva; Cozzolino, Anthony ...
The FASEB journal,
April 2018, 2018-04-00, Letnik:
32, Številka:
S1
Journal Article
Recenzirano
Odprti dostop
Polyamines are abundant in nature, and the methylation of polyamines is a common enzymatic step in plants, especially plants containing alkaloids. This includes the family of compounds called ...granatane alkaloids. Pomegranate (Punica granatum) is one of the most commonly known granatane alkaloid‐producing plants. Pomegranate extracts are widely used for their antioxidant, anti‐inflammatory, and anticarcinogenic effects. 1 One of the proposed enzymes in the hypothetical pathway for the formation of granatane alkaloids is cadaverine N‐methyl transferase.2 It is important to find a method of synthesis for N‐methyl cadaverine (N‐methylpentane‐1,5‐diamine) and other N‐methyl polyamines, because they can be utilized as a standard for quantification purposes as well as providing a positive control when evaluating enzymatic activities of putative alkaloid producing N‐methyl transferases. The synthesis of N‐methyl cadaverine was employed by utilizing a substitution reaction between N‐methylbenzylamine and 5‐bromo‐valeronitrile, removing the protecting group (or benzyl ring) attached to the methylated amine, and reduction of the nitrile. 3
This is from the Experimental Biology 2018 Meeting. There is no full text article associated with this published in The FASEB Journal.
The current work describes a simple low cost solution-based method to synthesis graphene silver (Gr/Ag) nanocomposite as electrode material in fabrication of flexible polymer solar cells (PSCs). ...Flexible and transparent Gr/Ag - based electrodes were easily prepared on a desired scale by spin coating of an aqueous solution of Gr/Ag nanocomposite on polyethylene terephthalate (PET) substrate at ambient conditions. With the optimization of the weight ratio of Gr/Ag and the electrode thickness, flexible electrodes with sheet resistance of as low as 83 kΩ sq
−1
and transmittance of 47% were achieved. These electrodes were then utilized as transparent anodes in the fabrication of flexible PSC devices, replacing ITO. Photovoltaic performance of the fabricated devices was evaluated as a function of the anode electrode thickness under three conditions; at rest, inward bending and outward bending. The introduction of Ag into Gr resulted in a significant improvement in open circuit voltage (
V
OC
), short circuit current density (
J
SC
) and power conversion efficiency (PCE) compared to that considered for Gr-based devices. The Gr/Ag-based devices showed
J
SC
of 1.46 mA cm
−2
and a
V
OC
of 0.71 V. Under bending, PSC devices showed considerably larger
V
OC
and
J
SC
compared to the rest position. Furthermore, PCE of the devices decreased about 5.6% when they were bent inward and increased about 34% as they were bent outward. This was in good agreement with the observed changes in the sheet resistance of the fabricated flexible electrodes under similar conditions. The advantages of the described method for fabrication of flexible transparent electrodes include simple solution-based process, production of Gr-based electrodes with high mechanical stability
via
a low cost and environmentally friendly method and finally, the compatibility and adaptability of the method with roll-to-roll manufacturing technique suitable for industrial production.
Photovoltaic characteristics of flexible graphene/Ag electrode - based polymer solar cells as a function of electrode thickness under bending deformation.
Antimony(III) alkoxide cages were designed as building blocks for predictable supramolecular self-assembly. Supramolecular synthons featuring two Sb···O secondary bonding interactions (SBIs), each ...SBI stronger than 30 kJ/mol, were used to drive the formation of the supramolecular architectures. Judicious choice of pendant groups provided predictable control over the formation of self-assembled 3D columnar helices, which crystallized with hollow morphologies, or a self-assembled 2D bilayer. The Sb–O stretching frequency provides a spectroscopic signature of Sb···O SBI formation.
A new air and moisture stable antimony thiolate compound has been prepared that spontaneously forms stable hollow vesicles. Structural data reveals that pnictogen bonding drives the self-assembly of ...these molecules into a reversed bilayer. The ability to make these hollow, spherical, and chemically and temporally stable vesicles that can be broken and reformed by sonication allows these systems to be used for encapsulation and compartmentalisation in organic media. This was demonstrated through the encapsulation and characterization of several small organic reporter molecules.
A new air and moisture stable antimony thiolate compound has been prepared that spontaneously forms stable hollow vesicles.
A new air and moisture stable antimony thiolate compound has been prepared that spontaneously forms stable hollow vesicles.
A new air and moisture stable antimony thiolate compound has been prepared ...that spontaneously forms stable hollow vesicles. Structural data reveals that pnictogen bonding drives the self-assembly of these molecules into a reversed bilayer. The ability to make these hollow, spherical, and chemically and temporally stable vesicles that can be broken and reformed by sonication allows these systems to be used for encapsulation and compartmentalisation in organic media. This was demonstrated through the encapsulation and characterization of several small organic reporter molecules.
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