Tetraarylborate polymer networks as single-ion conducting solid electrolytes

A new family of solid polymer electrolytes based upon anionic tetrakis(phenyl)borate tetrahedral nodes and linear bis-alkyne linkers is reported. Sonogashira polymerizations using tetrakis(4-iodophenyl)borate, tetrakis(4-iodo-2,3,5,6-tetrafluorophenyl)borate and tetrakis(4-bromo-2,3,5,6-tetrafluorophenyl)borate delivered highly cross-linked polymer networks with both 1,4-diethynylbeznene and a tri(ethylene glycol) substituted derivative. Promising initial conductivity metrics have been observed, including high room temperature conductivities (up to 2.7 × 10^–4 S cm^–1), moderate activation energies (0.25–0.28 eV), and high lithium ion transport numbers (up to t _Li⁺ = 0.93). Initial investigations into the effects of important materials parameters such as bulk morphology, porosity, fluorination, and other chemical modification, provide starting design parameters for further development of this new class of solid electrolytes.     

Synthesis of rhenium chelated MAG3 functionalized rosette nanotubes

Rosette nanotubes (RNTs) are discrete nanostructures self-assembled from a guanine–cytosine hybrid motif (G∧C) under aqueous conditions. These materials have substantial design flexibility and a range of applications, which are partly attributed to their diverse surface functionalization. Given the potential for interesting properties resulting from a metal-RNT construct, here we describe an oxorhenium-functionalized RNT. More specifically, we present the synthesis of a twin G∧C motif expressing the mercaptoacetyl triglycine (MAG₃) ligand. We then examine the chelation reaction of the MAG₃ with ReOCl₃(PPh₃)₂ and self-assemble the resulting ReO-MAG₃-G∧C conjugate into RNTs under DMSO and aqueous conditions.     

Synthesis of a tetracyclic G∧C scaffold for the assembly of rosette nanotubes with 1.7 nm inner diameter

The synthesis of a tetracyclic self-complementary molecule 4 for self-assembly into rosette nanotubes is presented. This new heterocycle has a core structure containing two pyrido[2,3-d]pyrimidine molecules fused together and features the Watson-Crick hydrogen bond donor-acceptor arrays of both guanine (G) and cytosine (C). Current methods to synthesize pyrido[2,3-d]pyrimidines require harsh conditions and long reaction times and result usually in low product yields. This is particularly problematic for the direct incorporation of functional groups that cannot withstand these conditions. Here, we present an efficient approach to access the multifunctional pyrido[2,3-d]pyrimidine intermediate 2 under relatively mild conditions using three regioselective S(N)Ar reactions at C2, C4, and C7 on the trichloro compound 1. The electron-withdrawing group and amino functionalities on 2 are then used as a handle to install the third and fourth rings of 4 using a Friedla?nder-type condensation followed by mixed urea synthesis and cyclization.     

Conformational analysis and inversion process in some perhydrodipyrido[1,2‐b;1′2′‐e]‐1,4,2,5‐ dioxadiazines

The stereoselectivity in the cyclodimerization of several six‐membered cyclic nitrones has been investigated. The configurational/conformational analysis of the dimers (i.e. perhydrodipyrido[1,2‐b;1′2′‐e]‐1,4,2,5‐dioxadiazines) has been carried out by NMR spectroscopy. The NMR spectra of the dimers at lower temperatures indicated the presence of either a single or two invertomer(s). The nitrogen inversion barriers are determined using complete line–shape analysis. The invertomer ratios have been used to estimate the relative energies associated with the cis and trans ring fusion in these tricycles. A mechanistic rationale for the observed stereochemistry of the dimerization process has been presented. Copyright © 2009 John Wiley & Sons, Ltd.     

The face selectivity of 1,3-dipolar cycloaddition reactions of 4-butyloxycarbonyl-3,4,5,6-tetrahydropyridine 1-oxide

A study of the stereo- and face selectivity of the cycloaddition reactions of a series of mono- and disubstituted alkenes with 4-butyloxycarbonyl-3,4,5,6-tetrahydropyridine 1-oxide has been carried out. Rate constants for the cycloaddition of the nitrone to methyl acrylate, styrene, and methyl methacrylate have been determined at various temperatures by ¹H NMR spectroscopy. The activation parameters indicate the concerted nature of the reaction. The 4-substituted nitrone is found to be more reactive than its unsubstituted counterpart 3,4,5,6-tetrahydropyridine 1-oxide. The addition reactions have displayed a very high degree of face selectivity (9:1), and those reactions in micellar media are found to be very efficient. Conformational analysis and peracid-induced ring opening of a cycloadduct has been carried out to give second-generation cyclic nitrones.