Hydrogen- and Halogen-Bonded Binary Cocrystals with Ditopic Components: Systematic Structural and Photoreactivity Properties That Provide Access to a Completed Series of Symmetrical Cyclobutanes

Abstract

A series of binary cocrystals involving the ditopic hydrogen-and halogen-bond (H-and X-bond, respectively) donors resorcinol (res) and hydroquinone (hq), and 1,3-and 1,4-diiodotetrafluorobenzene (1,3-and 1,4-di-I-tFb), respectively, cocrystallized with one of the three symmetric bipyridines trans-1,2-bis(n-pyridyl)ethylene (n,n′-bpe, where n = n′ = 2, 3, 4) is reported. The structures of the six novel cocrystals, (1,3-di-I-tFb)•(3,3′-bpe), 4(res)•3(3,3′-bpe), (1,3-di-I-tFb)•(4,4′-bpe), 3(hq)• 2(2,2′-bpe), (1,4-di-I-tFb)•(3,3′-bpe), and (hq)•(3,3′-bpe), are described. The cocrystals comprise components that assemble by either O−H•••N and O−H•••O H-bonds (res and hq) or N•••I X-bonds (1,3-and 1,4-di-I-tFb).The work completes a series of 18 cocrystals involving either the three dihydroxybenzenes catechol (cat), res, and hq or the three diiodotetrafluorobenzenes (1,2-, 1,3-, and 1,4-di-I-tFb) as H-or X-bond donors, respectively, with each of the three structurally isomeric symmetric bipyridines n,n′bpe. Our study demonstrates the significant consequences that minimally subtle variations to molecular structure of coformers can have for stoichiometric formulations, molecular packing, and solid-state photoreactivity. The work also provides access to a completed series of symmetrically substituted rctt-tetrakis(n-pyridyl)cyclobutanes (where: n = 2, 3, or 4).

Isolation of elusive cyclobutane ligands via a template-assisted photochemical [2 + 2] cycloaddition reaction and their utility in engineering crystalline solids

“…The dimer was further isolated by chromatography and was characterized by SCXRD. 37 The same group reported exhaustive works on systematic structural and photoreactivity studies by employing py-N⋯I halogen bonding to design several binary cocrystals that yielded both the symmetrical 38 and unsymmertical 39 cyclobutane compounds.…”

Tuning the Regioselectivity of Topochemical Polymerization through Cocrystallization of the Monomer with an Inert Isostere

“…Some of the approaches for tuning topochemical reactivity are by altering the stimulus, [11–14] and obtaining polymorphs having different reactivities, [15–20] both being trial‐and‐error approaches. However a more rational approach to tune the reactivity is by designing cocrystals, employing the crystal engineering tools [21–29] . In most of the cases, cocrystals have been used to make molecules that are non‐reactive in their pristine crystals, reactive [30–34] .…”

“…However a more rational approach to tune the reactivity is by designing cocrystals, employing the crystal engineering tools. [21][22][23][24][25][26][27][28][29] In most of the cases, cocrystals have been used to make molecules that are non-reactive in their pristine crystals, reactive. [30][31][32][33][34] Modifying the templates (coformers) have been shown to improve yield, regio/stereochemical outcome in [2+2] cycloaddition reactions.…”

Controlled Halogen-Bond-Involving Assembly of Double-σ-Hole-Donating Diaryliodonium Cations and Ditopic Arene Sulfonates

“…Specifically, we employed the isomeric 1,5- and 2,6-naphthalenedisulfonates as XB-accepting counterions of double-σ-hole XBs donating diaryliodonium cations. A related approach has recently been utilized for the construction of extended arrays in crystals of [Ph 2 I] 2 [M­(CN) 4 ] (M = Ni and Pd); other cases wherein di- and tetratopic XB acceptors were used have been reported in the past five years. − …”