Related Experiment Video
Updated: Aug 18, 2026

Thermal Scanning Conductometry (TSC) as a General Method for Studying and Controlling the Phase Behavior of Conductive Physical Gels
Published on: January 23, 2018
Cation effect on thermal transition of iota-carrageenan: a photon transmission study
1Department of Physics, Istanbul Technical University, Maslak 80626 Istanbul, Turkey pekcan@itu.edu.tr
Abstract:
Coil-to-double helix (c-h) and double helix-to-dimer (h-d) phase transitions of iota-carrageenan in various cation (CaCl2) solutions upon heating and cooling were studied using the photon transmission technique. Photon transmission intensity, Itr, was monitored against temperature to determine the (c-h) and (h-d) transition temperatures (Tch and Thd) and activation energies (DeltaEch and DeltaEhd). An extra dimer-to-dimer (d-d) transition was observed during cooling at low temperature region. However, upon heating dimers directly decompose into double helices by making dimer-to-double helix (d-h) transition. Further heating results in double helix-to-coil (h-c) transition at high temperature region. Tdh and Thc temperatures and Delta Edh and DeltaEhc activation energies were determined. It was observed that Thc and Tch temperatures and DeltaEch and DeltaEhc activation energies were found to be strongly correlated to the CaCl2 content in the system.
Related Concept Videos
Thermal Sigmatropic Reactions: Overview
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in 1,5-hexadiene, referred to as...
π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
π Electron Effects on Chemical Shift: Overview
UV–Vis Spectroscopy: Molecular Electronic Transitions
Atomic Spectroscopy: Effects of Temperature
At thermal equilibrium, the relative populations of excited and ground state atoms can be estimated using the Maxwell–Boltzmann distribution. For example, an increase in temperature from...
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.

