Helices are among the most common ordered structures in biological and synthetic polymers, but their formation involves more than local conformational preference. A finite helix must nucleate, grow, resist breaking, and maintain a selected handedness against thermal fluctuations. We develop a three-state Ising-like transfer-matrix theory in which each segment is coil-like, right-handed helical, or left-handed helical. This formulation separates ordinary helix--coil cooperativity from the persistence of handedness. The right--left symmetric problem decomposes into symmetric and antisymmetric sectors, giving two characteristic lengths: the helical correlation length $\xi_H$ and the chiral persistence length $\xi_\chi$. In the strongly helical rare-wall limit, $\xi_\chi\simeq (1/2)\exp[\beta(K+J)]$. A local chiral bias, motivated by the Ramachandran landscape, is then amplified over finite helical domains.
Weakly flexible, directed polymers can adopt a potentially infinite variety of conformations, some of them chiral. We develop a second-virial theory for semi-rigid polymers embedded in a nematic environment based on the assumption that the chains possess no intrinsic molecular chirality but can take on weakly helical c...
Achiral nematogens may exhibit transient chiral states that interconvert by thermal fluctuations due to low energetic barriers between left- and right-handed twisted conformations. Allowing for a thermodynamic equilibrium between the mirror-image enantiomers and accounting for favorable chiral interactions between like...
P. van der Schoot· Journal of Chemical Physics· 0 citations
This work presents a minimal coarse-grained molecular dynamics model for the coil-helix transition in polymers. We demonstrate that the addition of a Morse potential to a freely jointed chain with volume and bond potentials is sufficient to reproduce the essential thermodynamic features of the transition. From the simu...
Karthik C Sinha, Alexey A. Gavrilov, Artem M. Rumyantsev· Journal of Chemical Physics· 1 citation
Macromolecular coil-to-helix transitions simultaneously modify local geometry and persistence length, driving complex changes in overall chain size. Here, we apply the wormlike (persistent) chain model to both coil and helical fragments to examine how the degree of helicity, θ, and average helical fragment length, kh,...
Karthik C Sinha, Alexey A. Gavrilov, Artem M. Rumyantsev· Journal of Chemical Physics· 1 citation
Abiotic foldamers that switch between distinct, well-defined geometries are rare. Here, we report a structurally simple series of oligomers with alternating ortho-phenylene and 2,3-pyrazinylene repeat units. Deconvolution of variable-temperature 1H NMR spectra, with the help of ab initio chemical shift predictions, sho...
Ying Liao, Vipul Batra, G. P. Devkota et al.· Chemistry· 0 citations
