Emerging solid-state cycloaddition chemistry for molecular solar thermal energy storage.

Recently discovered designs of solid-state molecular solar thermal energy storage systems are illustrated, including alkenes, imines, and anthracenes that undergo reversible [2 + 2] and [4 + 4] photocycloadditions for photon energy storage and release. The energy storage densities of various molecular designs, from 6 kJ mol to 146 kJ mol (or up to 318 J g), are compared and summarized, along with effective strategies for engineering their crystal packing structures that facilitate solid-state reactions. Many promising molecular scaffolds introduced here highlight the potential for achieving successful solid-state solar energy storage, guiding further discoveries and the development of new molecular systems for applications in solid-state solar thermal batteries.

Mechanoactivated amorphization and photopolymerization of styryldipyryliums.

Conventional topochemical photopolymerization reactions occur exclusively in precisely-engineered photoactive crystalline states, which often produces high-insoluble polymers. To mitigate this, here, we report the mechanoactivation of photostable styryldipyrylium-based monomers, which results in their amorphization-enabled solid-state photopolymerization and produces soluble and processable amorphous polymers. A combination of solid-state nuclear magnetic resonance, X-ray diffraction, and absorption/fluorescence spectroscopy reveals the crucial role of a mechanically-disordered monomer phase in yielding polymers via photo-induced [2 + 2] cycloaddition reaction.

Topochemical Syntheses of Polyarylopeptides Involving Large Molecular Motions: Frustrated Monomer Packing Leads to the Formation of Polymer Blends.

We report the topochemical syntheses of three polyarylopeptides, wherein triazolylphenyl group is integrated into the backbone of peptide chains. We synthesized three different monomers having azide and arylacetylene as end-groups from glycine, L-alanine and L-valine. We crystallized these monomers and the crystal structures of two of them were determined by single-crystal X-ray diffractometry.

Cascading Effect of Large Molecular Motion in Crystals: A Topotactic Polymorphic Transition Paves the Way to Topochemical Polymerization.

A topochemical polymerization governed by a topotactic polymorphic transition is reported. A monomer functionalized with azide and an internal alkyne crystallized as an unreactive polymorph with two molecules in the asymmetric unit. The molecules are aligned in a head-to-head fashion, thereby avoiding the azide-alkyne proximity for the topochemical azide-alkyne cycloaddition (TAAC) reaction.

Tuning the Regioselectivity of Topochemical Polymerization through Cocrystallization of the Monomer with an Inert Isostere.

Regiochemistry of topochemical reactions depends on the crystal packing and biasing the regiochemistry necessitates precise crystal engineering. The pristine crystals of monomer 1 upon topochemical azide-alkyne cycloaddition (TAAC) reaction give a 1 : 1 blend of 1,4- and 1,5-triazole-linked polymers due to the presence of two self-sorted reactive conformers in the crystal. We designed a binary isomorphous cocrystal of monomer 1 and a structurally similar dummy molecule 2 to limit the number of reactive conformers of 1 to one and thus to get one type of polymer.

Topochemical Cycloaddition Reaction between an Azide and an Internal Alkyne.

Here we report the synthesis of a trisubstituted-1,2,3-triazole-linked polymer using a topochemical azide-alkyne cycloaddition (TAAC) reaction. A cyclitol-derived monomer having an azide and an internal alkyne group was designed. The four hydroxy groups present in this monomer dictate its crystal packing such that the monomer molecules are arranged head-to-tail, thereby placing the internal alkyne and the azide units of adjacent molecules proximally.

Polymers with advanced structural and supramolecular features synthesized through topochemical polymerization.

Polymers are an integral part of our daily life. Hence, there are constant efforts towards synthesizing novel polymers with unique properties. As the composition and packing of polymer chains influence polymer's properties, sophisticated control over the molecular and supramolecular structure of the polymer helps tailor its properties as desired.

Topochemical polymerizations for the solid-state synthesis of organic polymers.

Topochemical polymerizations are solid-state reactions driven by the alignment of monomers in the crystalline state. The molecular confinement in the monomer crystal lattice offers precise control over the tacticity, packing and crystallinity of the polymer formed in the topochemical reaction. As topochemical reactions occur under solvent- and catalyst-free conditions, giving products in high yield and selectivity/specificity that do not require tedious chromatographic purification, topochemical polymerizations are highly attractive over traditional solution-phase polymer synthesis.

Organogel-Derived Covalent-Noncovalent Hybrid Polymers as Alkali Metal-Ion Scavengers for Partial Deionization of Water.

We show that crown ethers (CEs) 1-5 congeal both polar and nonpolar solvents via their self-assembly through weak noncovalent interactions (NCIs) such as CH···O and CH···π interactions. Diisopropylidene-mannitol (6) is a known gelator that self-assembles through stronger OH···O H bonding. These two gelators together also congeal nonpolar solvents via their individual self-assembly.

CuBr/TBHP-mediated synthesis of N-acyl sulfonimidamides via the oxidative cross-coupling of sulfonimidamides and aldehydes.

N-Acyl sulfonimidamides were synthesized via a Cu-catalyzed double C-H/N-H activation protocol. The imino end of sulfonimidamides was acylated using aldehyde as the acylating agent and t-butyl hydrogen peroxide (TBHP) as the oxidant in acetonitrile (MeCN) at 82 °C. The mild reaction conditions afforded low-to-moderate yields of N-acyl sulfonimidamides with high structural diversity.