Lanthanide-Based Coordination Polymers Molecular Alloys Stability: A Thermochemical Approach

Area of Science:

• Materials Science
• Inorganic Chemistry
• Thermodynamics

Background:

• Lanthanide ions exhibit subtle chemical differences impacting material properties.
• Coordination polymers offer tunable structures for advanced applications.
• Molecular alloys present opportunities for novel material design.

Purpose of the Study:

• To investigate the thermodynamic principles governing lanthanide-based coordination polymer molecular alloys.
• To determine the solubility constants of homo-lanthanide coordination polymers.
• To explore the factors influencing the stability of mixed-lanthanide coordination polymer alloys.

Main Methods:

• Experimental determination of solubility constants for isostructural homo-lanthanide coordination polymers ([Ln2(bdc)3(H2O)4]∞).
• Synthesis and characterization of two series of isostructural molecular alloys ([Ln2Ln'2-2x(bdc)3(H2O)4]∞).
• Thermodynamic analysis focusing on configurational entropy as a stabilizing factor.

Main Results:

• Significant variations in solubility were observed among homo-lanthanide coordination polymers despite ion similarities.
• Solubility constants were experimentally determined for Ln = La-Er plus Y.
• Molecular alloys, whether based on heavy or light lanthanides, demonstrated stabilization driven by configurational entropy.
• The solubility differences of homo-nuclear compounds did not preclude alloy stabilization.

Conclusions:

• Configurational entropy is the primary driving force for the stabilization of lanthanide coordination polymer molecular alloys.
• Understanding solubility variations is crucial for designing and predicting the behavior of these materials.
• This study provides fundamental thermodynamic insights into the formation and stability of complex lanthanide-based materials.