Coordination chemistry
Unsymmetrical ligands still make one Pd2L4 cage isomer
Open access · cc by · source: Europe PMC
Steric and geometric ligand design plus solvent polarity steer unsymmetrical dipyridyl ligands into a single cis or trans Pd2L4 cage rather than a statistical isomer mix.
Study at a glance
- Design
- Other — Unsymmetrical bis-pyridyl ligands assembled with Pd(II) to control cis/trans Pd2L4 isomers
- N
- Coordination-cage synthesis/DFT — no sample N
- Population
- Pd2L4 coordination cages in MeCN/DMSO
- Outcome
- Ligand sterics locking preferred Pd2L4 cage isomers
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
Methyl steric bias and non-coplanar donors can lock a single cis-Pd2L4 isomer; ligand 1 gives trans in MeCN but a cis/trans mix in DMSO; DFT ranked isomers by several kJ mol−1.
Methodology
Authors synthesised unsymmetrical bis-pyridyl ligands, assembled them with [Pd(CH3CN)4](BF4)2 in acetonitrile or DMSO, and assigned cage isomers by 1H/DOSY NMR, MS, variable-temperature NMR, SCXRD and DFT relative energies.
Limitations
The work does not demonstrate guest binding, catalysis, or multifunctional cavities inside these isomerically pure cages.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
¹H, DOSY and variable-temperature NMR, with crystallography and DFT, can lock which Pd₂L₄ cage isomer formed. Methyl steric bias and non-coplanar donors favoured a single cis isomer; ligand 1 was trans in MeCN but a cis/trans mix in DMSO. Guest binding and catalysis inside those cages were not shown.
Evidence for the claim as stated.
A missing peak can mean opposite things. In oocytes the ligand-bound G-quadruplex vanished, which the authors read as extra binding or precipitation — not as 'the complex did not form.' In cage isomer assignment, extra peaks mean a second isomer is present. Treating silence as non-binding is unsafe.
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
A missing peak can mean opposite things. In oocytes the ligand-bound G-quadruplex vanished, which the authors read as extra binding or precipitation — not as 'the complex did not form.' In cage isomer assignment, extra peaks mean a second isomer is present. Treating silence as non-binding is unsafe.
- Supports · In-cell NMR of a DNA G-quadruplex and ligand
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