Rational design and topochemical synthesis of polymorphs of a polymer

Sureshan, Kana M.; Athiyarath, Vignesh; Mathew, Liby Ann; Zhao, Yakai; Ramamurthy, U.; Khazeber, Ravichandran

doi:10.1039/d3sc00053b

Cited by 6 publications

(1 citation statement)

References 78 publications

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“…12, including the chemical structures of monomers and polymers and the transformation process in the single-crystal state. 93,[95][96][97][98][151][152][153][154][155][156][157][158] In general, hydrogen-bonding interactions, such as O-HÁ Á ÁO, N-HÁ Á ÁO, and N-HÁ Á ÁN, are the main noncovalent driving force for aligning azide and alkyne or ene-substituted derivatives in orientations suitable for their proximity-driven cycloaddition reaction in crystals. The arrangement of azide and alkyne or ene carbohydrates (1D-P-22, 29, 30), nucleosides (1D-P-23), and peptides (1D-P-24, 25, 26, 27, 28, 31, 32, 33, 34) have been successfully exploited for their topochemical azide-alkyne and azide-ene cycloadditions.…”

Section: Review Articlementioning

confidence: 99%

Single-crystal polymers (SCPs): from 1D to 3D architectures

Wang,

Jin,

Zhang

et al. 2023

Chem. Soc. Rev.

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Section: Review Articlementioning

confidence: 99%

Single-crystal polymers (SCPs): from 1D to 3D architectures

Wang,

Jin,

Zhang

et al. 2023

Chem. Soc. Rev.

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Large Molecular Rotation in Crystal Changes the Course of a Topochemical Diels–Alder Reaction from a Predicted Polymerization to an Unexpected Intramolecular Cyclization

Lal,

Madhusudhanan,

Sureshan

2024

Angewandte Chemie

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A designed anthracene‐based monomer for topochemical Diels‐Alder cycloaddition polymerization crystallized with head‐to‐tail arrangement of molecules, as revealed by single‐crystal X‐ray diffraction (SCXRD) analysis. The diene and dienophile units of adjacent monomer molecules are aligned at an average distance of 4.6 Å, suggesting a favorable crystalline arrangement for their intermolecular Diels‐Alder cycloaddition reaction to form a linear polymer . Surprisingly, heating the monomer crystals at a temperature above 125 °C resulted in the formation of intramolecular Diels‐Alder cycloadduct, which could be characterized by various spectroscopy and SCXRD analysis. Various time‐dependent studies such as NMR, PXRD, and DSC, studies established that the reaction followed topochemical pathway. Schmidt’s topochemical postulates are generally used to predict the topochemical reactivity and product, by analyzing the crystal structure of the reactant. Though the crystal arrangement predicted polymerization, upon heating the molecule avoided this pathway by undergoing a large rotation to form an intramolecular cycloadduct. Theoretical calculations supported the feasibility of the rotation, exploiting the flexibility of the molecule and voids present. These findings caution that the reliance on Schmidt’s criteria for topochemical reactions may sometimes be misleading, especially in heat‐induced reactions.

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Elucidation of Substituent‐Responsive Reactivities via Hierarchical and Asymmetric Assemblies in Crystalline p‐Quinodimethane Derivatives

Itoh

Kondo

Suzuki

et al. 2023

Chemistry A European J

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We propose a mechanism for substituent‐responsive reactivities of p‐quinodimethane derivatives with four ester groups through their hierarchical and asymmetric assembly modes. Four asymmetric 7,8,8‐tris(methoxycarbonyl)‐p‐quinodimethanes with a 7‐positioned ethoxycarbonyl (2a(H)), 2’‐fluoroethoxycarbonyl (2b(F)), 2’‐chloroethoxycarbonyl (2c(Cl)), or 2’‐bromoethoxycarbonyl (2d(Br)) were synthesized and crystallized. 2a(H), 2b(F) and 2d(Br) afforded only one shape crystal, while 2c(Cl) did two polymorphic 2c(Cl)‐a and 2c(Cl)‐b. UV‐irradiation induced topochemical polymerization for 2a(H), no reactions for 2b(F) and 2c(Cl)‐a, and [6+6] photocycloaddition dimerization for 2c(Cl)‐b and 2d(Br). Such substituent‐responsive reactivities and crystal structures were compared with those of the known symmetric 7,7,8,8‐tetrakis(alkoxycarbonyl)‐p‐quinodimethanes such as 7,7,8,8‐tetrakis(methoxycarbonyl)‐ (1a(Me)‐a and 1a(Me)‐b), 7,7,8,8‐tetrakis(ethoxycarbonyl)‐ (1b(Et)), and 7,7,8,8‐tetrakis(bromoethoxycarbonyl)‐ (1c(BrEt)). The comparative study clarified that the reactivities and crystal structures are classified into four types that link to each other. This linkage is understandable when we analyze the crystal structures through the following hierarchical and asymmetric assemblies; conformers, dimers, 1D‐columns, 2D‐sheets, and 3D‐stacked sheets (3D‐crystals). This supramolecular viewpoint is supported by intermolecular interaction energies among neighbored molecules with the density functional theory (DFT) calculation. Such research enables us to elucidate the substituent‐responsive reactivities of the crystals, and reminds us of the selection of the right path in a so‐called “maze game”.

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Rational design and topochemical synthesis of polymorphs of a polymer

Abstract: Packing a polymer in different ways can give polymorphs of the polymer having different properties. β-turn forming peptides such as 2-aminoisobutyric acid (Aib)-rich peptides adopt several conformations by varying dihedral...

Cited by 6 publications

References 78 publications

Single-crystal polymers (SCPs): from 1D to 3D architectures

Single-crystal polymers (SCPs): from 1D to 3D architectures

Large Molecular Rotation in Crystal Changes the Course of a Topochemical Diels–Alder Reaction from a Predicted Polymerization to an Unexpected Intramolecular Cyclization

Elucidation of Substituent‐Responsive Reactivities via Hierarchical and Asymmetric Assemblies in Crystalline p‐Quinodimethane Derivatives

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