Unraveling weak interactions in aniline-pyrrole dimer clusters

Energy decomposition analysis based on broken symmetry unrestricted density functional theory

In this paper, the generalized Kohn-Sham energy decomposition analysis (GKS-EDA) scheme is extended to molecular interactions in open shell singlet states, which is a challenge for many popular EDA methods due to the multireference character. Based on broken symmetry (BS) unrestricted density functional theory with a spin projection approximation, the extension scheme, named GKS-EDA(BS) in this paper, divides the total interaction energy into electrostatic, exchange-repulsion, polarization, correlation, and dispersion terms. Test examples include the pancake bond in the phenalenyl dimer, the ligand interactions in the Fe(ii)-porphyrin complexes, and the radical interactions in dehydrogenated guanine-cytosine base pairs and show that GKS-EDA(BS) is a practical EDA tool for open shell singlet systems.

Weak interactions cause selective cocrystal formation of lanthanide nitrates and tetra-2-pyridinylpyrazine

Two series of cocrystals Ln(NO₃)₅·H₂TPPZ are synthesized enlightening the lanthanide contraction effect and weak hydrogen bonding interactions in determining the selective cocrystallization, stability and energy transfer for luminescence.