Reentrant Spin-Glass Behavior in Cobalt(II) Based Coordination Polymers

Abstract

Correlation of molecular structure and its magnetic property gives a better understanding toward the design of magnetic materials with long-range magnetic order. Here we report two new cobalt-based coordination polymers that exhibited coexistence of long-range ferromagnetic (FM) order and spin-glass (SG) transition at below T c . Different orientation of magnetic moments, arrangements, and variation in connectivity with the ligands might be responsible for the SG transition. The SG transition was characterized by bifurcation of zero-field-cooled and field-cooled splitting at T f ≈ 9.9 K (for both compounds) and AC susceptibility measurements. DC magnetization revealed the FM transition at high temperature, followed by a low-temperature SG transition. Moreover, the peculiarity found in low-temperature χ′′(T) can be attributed to the complex interplay between antiferromagnetic and ferromagnetic interactions and the coexistence of the long-range FM order and SG phase. Optical bandgap and temperature-dependent resistivity measurements showed that these compounds are semiconducting in nature.

Conductive Metal‐Organic Frameworks: Electronic Structure and Electrochemical Applications

“…Whereas later MOF (Cd‐1 ortho ) was nearly insulator because of offset dimer orientation rendering no efficient intimate π‐π interaction. A similar observation was realised in two Co (II)‐triazine based frameworks, where slipped parallel orientation of triazine dimers inferred low conductivity despite closely packed triazine dimers [132] . However, variable temperature resistivity revealed its semiconducting nature.…”

A Three‐Dimensional Pentanuclear Co(II) Coordination Polymer: Structural Topology, Hirshfeld Surface Analysis and Magnetic Properties

“…In the last few decades, the design and synthesis of 3dimensional (3D) polynuclear coordination polymers (CPs) containing paramagnetic centers (spin clusters) have attracted special attention due to their intriguing topologies and fascinating framework architectures with interesting magnetic properties. [1][2][3][4][5][6][7][8] The CPs encompass a large group of compounds, formed by central metal ions and organic linkers through selfassembly process under the controlled conditions (temperature, solvent, pH, etc.). [9,10] The magnetic materials derived from these CPs are highly preferred over the traditional inorganic magnets due to their structural tenability and electronic versatilities.…”