Saikat Kumar Seth

Use of π–π forces to steer the assembly of chromone derivatives into hydrogen bonded supramolecular layers: crystal structures and Hirshfeld surface analyses

Two chromone derivatives C11H10O3 (1) and C11H10O2 (2) have been synthesized and characterized by X-ray structural studies with a detailed analysis of the Hirshfeld surfaces and fingerprint plots facilitating a comparison of intermolecular interactions in building different supramolecular architectures. The title compounds are associated through π–stacking interactions and the linear stacking of π–π forces can be thought as the influencing agent for the organization of the title compounds into hydrogen bonded supramolecular layers and are responsible as well for the strengthening of the molecular assembly. Investigation of the intermolecular interactions and crystal packing via Hirshfeld surface analysis reveals that more than two-thirds of the close contacts are associated with weak interactions. The fingerprint plots demonstrate that these weak interactions are important for both local and crystal packing. A comparison of the Hirshfeld surface in the compounds with similar substituted chromone derivatives in the Cambridge Structural Database (CSD) has been presented.

Insight into supramolecular self-assembly directed by weak interactions in acetophenone derivatives: crystal structures and Hirshfeld surface analyses

The crystallographic study of four acetophenone derivatives (1–4) is reported in the context of crystal engineering with a detailed analysis of Hirshfeld surfaces and fingerprint plots facilitating a comparison of intermolecular interactions in building different supramolecular self-assemblies. The X-ray study reveals that molecules of 1–4 are linked by cooperative weak C–H⋯O, C–H⋯π and π⋯π stacking interactions which are responsible for the formation and strengthening of molecular assembly. The substituting benzyl units are used as a potential scaffold for designing supramolecular self-assemblyvia C–H⋯π forces. Investigation of Hirshfeld surface analysis reveals a much more detailed scrutiny in comparison to these weak forces experienced by each compound. A comparison of Hirshfeld surfaces in the title derivatives with similar substituted and unsubstituted structures retrieved from the Cambridge Structural Database (CSD) has been presented.

Anion-π interaction stitching 2-D layers formed by self-assembly of cations of a mononuclear copper(II) complex: synthesis, crystal structure and magnetism of [Cu(OAc)(2,2′-dypam)2](ClO4) [HOAc = acetic acid, 2,2′-dypam = 2,2′-dipyridylamine]

A mononuclear Cu(II) compound [Cu(OAc)(2,2′-dypam)2](ClO4) (1), where HOAc and 2,2′-dypam are, respectively, acetic acid and 2,2′-dipyridylamine, has been synthesized and characterized by single crystal X-ray diffraction analysis. The cations of 1 link by N–H ··· O hydrogen bonds to form infinite 1-D zig-zag chains, which run along the b axis. Two adjacent chains along the c axis are joined by C–H ··· O hydrogen bonds to form a 2-D network. These 2-D layers are further bridged by perchlorate anions via weak anion-π interactions that act as a supramolecular glue to build the 3-D supramolecular network. Variable temperature (1.7–300 K) magnetic measurements revealed very weak intermolecular antiferromagnetic interactions at temperatures below 20 K between Cu(II) ions mediated by hydrogen bonds, C–H ··· π and π ··· π interactions. At temperatures ≥20 K, susceptibility data corresponds to isolated Cu(II) ions, indicating that the weak interactions affect the magnetism of 1 only at very low temperatures.