Co-crystal sustained by π-type halogen-bonding inter-actions between 1,4-di-iodo-perchloro-benzene and naphthalene

The formation and crystal structure of a co-crystal based upon 1,4-di-iodo-perchloro-benzene (C6I2Cl4) as the halogen-bond donor along with naphthalene (nap) as the acceptor is reported. The co-crystal [systematic name: 1,2,4,5-tetra-chloro-3,6-di-iodo-benzene-naphthalene, (C6I2Cl4)·(nap)] generates a chevron-like structure that is held together primarily by π-type halogen bonds (i.e. C-I⋯π contacts) between the components. In addition, C6I2Cl4 also inter-acts with the acceptor via C-Cl⋯π contacts that help stabilize the co-crystal. Within the solid, both aromatic components are found to engage in offset and homogeneous face-to-face π-π stacking inter-actions. Lastly, the halogen-bond donor C6I2Cl4 is found to engage with neighboring donors by both Type I chlorine-chlorine and Type II iodine-chlorine contacts, which generates an extended structure.

Halogen-Bond Mediated [2+2] Photodimerizations: À la Carte Access to Unsymmetrical Cyclobutanes in the Solid State

The ditopic halogen-bond (X-bond) donors 1,2-, 1,3-, and 1,4-diiodotetrafluorobenzene (1,2-, 1,3-, and 1,4-di-I-tFb, respectively) form binary cocrystals with the unsymmetrical ditopic X-bond acceptor trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene (2,4-bpe). The components of each cocrystal (1,2-di-I-tFb)·(2,4-bpe), (1,3-di-I-tFb)·(2,4-bpe), and (1,4-di-I-tFb)·(2,4-bpe) assemble via N···I X-bonds. For (1,2-di-I-tFb)·(2,4-bpe) and (1,3-di-I-tFb)·(2,4-bpe), the X-bond donor supports the C=C bonds of 2,4-bpe to undergo a topochemical [2+2] photodimerization in the solid state: UV-irradiation of each solid resulted in stereospecific, regiospecific, and quantitative photodimerization of 2,4-bpe to the corresponding head-to-tail (ht) or head-to-head (hh) cyclobutane photoproduct, respectively.

Cooperative non-covalent interactions and synthetic feed as driving forces to structural diversity within organic co-crystals containing isosteric perhalobenzenes

The formation of three co-crystals based upon a pair of isosteric halogen-bond donors, namely 1,4-diiodoperchlorobenzene and 1,4-diiodoperfluorobenzene, along with the acceptor trans-1-(4-methylbenzoate)-2-(4-pyridyl)ethylene is reported. Along with the varied stoichiometric ratios...

Controlling Topology within Halogen-Bonded Networks by Varying the Regiochemistry of the Cyclobutane-Based Nodes

The formation of a pair of extended networks sustained by halogen bonds based upon two regioisomers of a photoproduct, namely rctt-1,3-bis(4-pyridyl)-2,4-bis(phenyl)cyclobutane (ht-PP) and rctt-1,2-bis(4-pyridyl)-3,4-bis(phenyl)cyclobutane (hh-PP), that have varied topology is reported. These networks are held together via I⋯N halogen bonds between the photoproduct and the halogen-bond donor 1,4-diiodoperchlorobenzene (C₆I₂Cl₄). The observed topology in each solid is controlled by the regiochemical position of the halogen-bond accepting 4-pyridyl group. This paper demonstrates the ability to vary the topology of molecular networks by altering the position of the halogen bond acceptor within the cyclobutane-based node.

Exploring the Electronic Properties of Extended Benzofuran-Cyanovinyl Derivatives Obtained from Lignocellulosic and Carbohydrate Platforms Raw Materials

Two series of linear extended benzofuran derivatives associating cyanovinyl unit and phenyl or furan moieties obtained from benzaldehyde-lignocellulosic (Be series) or furaldehyde -saccharide (Fu series) platforms were prepared in order to investigate their emission and electrochemical properties. For the fluorescence in solution and solid states, contrasting results between the two series were demonstrated. For Be series a net aggregation induced emission effect was observed with high fluorescence quantum yield for the solid state. A [2+2] cycloaddition under irradiation at 350 nm was also revealed for one derivative of Be series. In contrast, for Fu series the fluorescence in solution is higher than in the solid state. The X-ray crystallography studies for the compounds reveal the formation of strong π-π stacking for the derivatives without emissive property in the solid state and the presence of essentially lateral contacts for emissive compounds. Taking advantage of the propensity to develop 2D π-stacking mode for the more extended derivative with a central furan cycle, organic field effect transistors presenting hole mobility have been made.

4-vinylpyridine derivatives: Protonation, methylation and silver(I) coordination chemistry

( E)-4-[2-(Pyridin-4-yl)vinyl]benzaldehyde, containing both a 4-vinylpyridine and an aldehyde functionality, is utilized to develop new, highly conjugated chalcone compounds and a bis-Schiff base azine compound. The chalcone-containing compounds are further explored for their protonation, methylation and silver(I) coordination chemistry using the pyridine moiety. In parallel, a cyano-containing analogue, ( E)-4-[2-(pyridin-4-yl)vinyl]benzonitrile is also synthesized and studied for its silver(I) coordination chemistry. These new compounds are fully characterized by mass spectrometry, elemental analysis and spectroscopic techniques. The methylated product of ( E)-1-(9-anthryl)-3-{4-[2-(pyridin-4-yl)vinyl]phenyl}prop-2-en-1-one and a silver complex of ( E)-4-[2-(pyridin-4-yl)vinyl]benzonitrile are structurally determined by X-ray crystallography.

Fluorine as a robust balancer for tuning the reactivity of topo-photoreactions of chalcones and the photomechanical effects of molecular crystals

The higher the number of fluorine atoms, the higher the topological photo-induced [2 + 2] cycloaddition reactivity of chalcones.

Iodoperchlorobenzene acts as a dual halogen-bond donor to template a [2 + 2] cycloaddition reaction within an organic co-crystal

The formation of three isostructural co-crystals that utilize iodoperchlorobenzene as a dual halogen-bond donor is reported.

Blue- and white-light-emitting 2D-coordination polymers and their solid-state photodimerization reaction

Two Pb(ii) coordination polymers (CPs) isolated and show 2D-sheet-like structures. CPs with the formate, undergoes solid-state photodimerization and displays blue emission. While 2D sheet with acetate is photostable and show white-light emission.

Crystal structure and photoreactivity of a halogen-bonded cocrystal based upon 1,2-diiodoperchlorobenzene and 1,2-bis(pyridin-4-yl)ethylene

The formation of a photoreactive cocrystal based upon 1,2-diiodoperchlorobenzene (1,2-C₆I₂Cl₄) and trans-1,2-bis(pyridin-4-yl)ethylene (BPE) has been achieved. The resulting cocrystal, 2(1,2-C₆I₂Cl₄)·(BPE) or C₆Cl₄I₂·0.5C₁₂H₁₀N₂, comprises planar sheets of the components held together by the combination of I...N halogen bonds and halogen-halogen contacts. Notably, the 1,2-C₆I₂Cl₄ molecules π-stack in a homogeneous and face-to-face orientation that results in an infinite column of the halogen-bond donor. As a consequence of this stacking arrangement and I...N halogen bonds, molecules of BPE also stack in this type of pattern. In particular, neighbouring ethylene groups in BPE are found to be parallel and within the accepted distance for a photoreaction. Upon exposure to ultraviolet light, the cocrystal undergoes a solid-state [2 + 2] cycloaddition reaction that produces rctt-tetrakis(pyridin-4-yl)cyclobutane (TPCB) with an overall yield of 89%. A solvent-free approach utilizing dry vortex grinding of the components also resulted in a photoreactive material with a similar yield.

A diamondoid net sustained by halogen bonds: employing a cyclobutane to generate a tetrahedral architecture

A purely organic dia net sustained by halogen bonds that contains nodes comprised of rctt-tetrakis (4-pyridyl) cyclobutane, obtained from a solid-state photoreaction, is reported.