Morpholino-Substituted BODIPY Species: Synthesis, Structure and Electrochemical Studies

Halogen Bond Motifs in Cocrystals of N,N,O and N,O,O Acceptors Derived from Diketones and Containing a Morpholine or Piperazine Moiety

In this study, we investigate the halogen bond acceptor potential of oxygen and nitrogen atoms of morpholine and piperazine fragments when they are peripherally located on N,O,O or N,N,O acceptor molecules. We synthesized four acceptor molecules derived from either acetylacetone or benzoylacetone and cocrystallized them with 1,4-diiodotetrafluorobenzene and 1,3,5-triiodotrifluorobenzene. This resulted in eight cocrystals featuring different topicities and geometric dispositions of donor atoms. In all cocrystals, halogen bonds are formed with either the morpholinyl oxygen atom or the terminal piperazine nitrogen atom. The I···O_morpholine halogen bonds feature lower relative shortening values than I···N_terminal, I···O_carbonyl, and I···N_proximal halogen bonds. The N and O halogen bond acceptor sites were evaluated through calculations of molecular electrostatic potential values.

Halogen-Bonded BODIPY Frameworks with Tunable Optical Features*

The ability to tune the optical features of BODIPY materials in the solid state is essential for their photorelated application and requires efficient control of the crystal packing. In this study, such control of BODIPY supramolecular assemblies was achieved by deliberate design and synthesis of a BODIPY containing a strong halogen-bond (XB) acceptor (-NO₂ ) and donor (I, Br) to mediate XB interactions. The di-halogenated structures formed isostructural mono-coordinate motif B3, B4 (1D tubular structure) and symmetric bifurcated motif B4-II (1D zigzag chains structure) through N-O⋅⋅⋅I, Br XB interactions. These XB interactions promote singlet-to-triplet intersystem crossing and triplet-to-singlet reverse intersystem crossing due to partial delocalization of oxygen electrons onto Br and I, which leads to unexpected fluorescence enhancement of B4-II. Finally, the indirect optical band gaps of B3, B4 and B4-II were amenable to tuning in the range of 1.85-2.50  eV by XB-driven crystal packings.

Modulation of supramolecular self-assembly of BODIPY tectons via halogen bonding

In this study, the efficiency of halogen bonding strategies to control over the supramolecular assemblies of boron dipyrromethene (BODIPY) (B-1, B-2, and B-3) derivatives was explored.

Carbon (sp3) tetrel bonding mediated BODIPY supramolecular assembly via unprecedented synergy of Csp3⋯N and Csp3⋯F pair interactions

Here, we present the first example of sp³ hybridized carbon centered (C_sp3) tetrel bonding mediated 3D BODIPY assembly via the exceptional synergy of C_sp3⋯N and C_sp3⋯F pair interactions.