Gonzalo Campillo-Alvarado

Reed College · Department of Chemistry

The ability of organoboronic acids to direct intermolecular [2 + 2] photodimerizations in the solid state is identified. The reactivity of 1,2-bis(4-pyridyl)ethylene (bpe) within cocrystals of discrete hydrogen-bonded molecular assemblies generates rctt-tetrakis(4-pyridyl)cyclobutane (tpcb) stereoselectively and in up to quantitative yield. Dry gri...

B←N coordination supports a [2+2] photodimerization in the solid state. The bond is defined by an orthogonal interaction between stilbazole and a phenylboronic ester to enable a stereocontrolled and rapid photoreaction. The cyclobutane photoproduct affords a novel diboron bis‐tweezer adduct that is used to separate a mixture of benzene and thiophen...

We report channel confinement properties of an electron-deficient boron host derived from the orthogonal B←N interaction between a boronic ester and trans-pentafluorostilbazole. The boron host forms one-dimensional channels in the crystalline solid state when crystallized with common electron-rich aromatic petrochemicals (i.e., benzene, toluene, o-...

We report supramolecular repurposing of Emtricitabine (FTC, trade name: Emtriva®), a blockbuster FDA-approved anti-HIV agent. FTC is revealed to act as a hydrogen-bonded cleft for bipyridine recognition. The supramolecular repurposing...

We describe the use of perfluorophenyl embraces and boron coordination (B ← N) to enhance dichroism in single crystals of an asymmetric azo chromophore. Specifically, a tripod-shaped boron adduct comprised of tris(pentafluorophenyl)borane (BCF) and 4-phenylazopyridine (4PAzP) self-assembles as supramolecular helices through perfluorophenyl embraces...

Cocrystallizations of diboronic acids (1,3‐benzenediboronic acid ( 1,3‐bdba ), 1,4‐benzenediboronic acid ( 1,4‐bdba ) and 4,4’‐biphenyldiboronic acid ( 4,4’‐bphdba )) and bipyridines (1,2‐bis(4‐pyridyl)ethylene ( bpe ) and 1,2‐bis(4‐pyridyl)ethane ( bpeta )) generated the hydrogen‐bonded 1:2 cocrystals [( 1,4‐bdba )( bpe ) 2 ] ( 1 ), [( 1,4‐bdba )(...

The dynamics of three guests: benzene (ben), naphthalene (nap), and xylene (xyl) included in the isostructural cavities of tetrameric [(2fbe)2(bpy)⊃guest]4 cages were examined using single-crystal X-ray diffraction, thermogravimetric analysis, variable-temperature solid-state ²H NMR spectroscopy, and molecular dynamics simulations. The inclusion co...

We report on the control of π-stacking modes (herringbone vs slipped-stack) and photophysical properties of 9,10-bis((E)-2-(pyridin-4-yl)vinyl)anthracene (BP4VA), an anthracene-based organic semiconductor (OSC), by isosteric cocrystallization (i.e., the replacement of one functional group in a coformer with another of “similar” electronic structure...

Self-assembled complexes utilizing the ditopic dative bond acceptor 1,3-diboronic acid with catechol and complementary U-shaped donors in the form of 1,8-dipyridylnaphthalenes (1,8-bis(4-pyridyl)naphthalene (DPN), 1,8-bis(4-ethylenylpyridyl)naphthalene (DEPN), and 1,8-bis(4-ethynylpyridyl)naphthalene (DAPN)) yielded discrete two-component structure...

We describe hydrogen bonds (i.e., N+-H···N) in combination with cation···π interactions to enable a cascade-like [2+2] photodimerization of 4-stilbazole in a salt cocrystal. A four-component crystal assembly is composed of photoactive pyridinium ion pair 4-stilbzH+ (4-stilbz = trans-1-(4-pyridyl)-2-(phenyl)ethylene) and photostable molecule pair 4-...

The chemistry that occurs within confined spaces is the product of a collection of forces, often beyond the molecule, and is not easily ascribed to singular factors. There is a breadth of material types that can define a confined space (e.g. macrocycles, interlocked molecules, porous and non-porous crystals, organic and inorganic/coordination cages...

The development of organic solids for applications in materials science requires a fundamental understanding of how close packing of molecules can affect structure and function. We report here nonporous organic crystals that release entrapped guest molecules upon application of UV light. We show components of binary cocrystal solvates to undergo an...

This Account describes work by our research group that highlights opportunities to utilize organoboron molecules to direct chemical reactivity in the organic solid state. Specifically, we convey a previously unexplored use of hydrogen bonding of boronic acids and boron coordination in boronic esters to achieve [2+2]-photocycloadditions in crystalli...

We report on B←N coordination to support a single-crystal-to-single-crystal reaction in the solid state. A [2 + 2] photodimerization is achieved with face-to-face π-stacks of monotopic B←N adducts composed of a phenylboronic acid catechol ester and an alkene with a terminal thiophene group. The photoreaction generates a ditopic B-adduct involving a...

Cocrystallization of a nonconductive boron based-host with aromatic guests generates conductive cocrystals. Carrier mobilities of the cocrystals with either pyrene or tetrathiafulvalene were measured using conducting probe atomic force microscopy. The incorporation of the π-rich aromatic guests results in electrically conductive cocrystals. The coc...

We describe the use of immobilized deoxyribonucleic acid (DNA) in a silica matrix as a biorecognition agent for the detection of albendazole sulfoxide (ASU), the primary metabolite of albendazole and a suspected teratogenic and embryotoxic agent. The biomaterial (DNA-containing gel) was synthesized by physical entrapment of salmon sperm in an inorg...

A single-crystal-to-single-crystal (SCSC) photodimerization is achieved using Au(I) coordination and aurophilic interactions. The rigid Au2(dppbz)(CF3COO)2 precursor (dppbz = 1,2-bis(diphenylphosphino)benzene) self-assembles with 1,2-trans-bis(4-pyridyl)ethylene (bpe) to afford a discrete [Au4(dppbz)2(bpe)2]4+ macrocycle in the solid state. The alk...

The ability of 2,4,6-tri-halophenols (3X-phOH) (where: X = Fl, Cl or Br) to enable reactivity of 1,2-bis(4-pyridyl)ethylene (bpe) in the solid state via cocrystallization is reported. The trihalophenols display structure behavior defined by infinite face-to-face π⋅⋅⋅π contacts and hydrogen bonds as pure solids that we show can be transferred to bin...

B←N coordination supports a [2+2] photodimerization in the solid state. The bond is defined by an orthogonal interaction between stilbazole and a phenylboronic ester to enable a stereocontrolled and rapid photoreaction. The cyclobutane photoproduct affords a novel diboron bis‐tweezer adduct that is used to separate a mixture of benzene and thiophen...

Photoreactive Ag(I) complexes of p-toluenesulfonate ions with the unsymmetrical alkene trans-1-(4-acetoxyphenyl)-2-(2-pyridyl)ethylene 1 is reported. The crystal [Ag(p-tol)(1)2]•(H2O) (p-tol = p-toluenesulfonate) undergoes a [2 + 2] photocycloaddition reaction in quantitative yield to afford the head-to-tail (ht) photoproduct rctt-1,3-bis(2-pyridyl...

We report the discovery of three polymorphs of the very recently FDA-approved boron-containing API Crisaborole. Crisaborole displays polymorphism based on the syn– (Form I) and anti– (Form II) conformations of the hydroxyl group of the oxaborole ring as shown by single-crystal X-ray analysis. Forms I and II were discovered based on the availability...

A series of 2:1 fluorinated arylboronic ester adducts with 4,4′-bipyridine sustained by N→B dative bonds have been synthesized. The degree of fluorination in the arylboronic esters derived from catechol is shown to modulate the molecular conformation of the coordinated boronic ester moieties and the intermolecular interactions by means of C−H···F a...

Cocrystals of the FDA-approved boron-containing API Tavaborole (AN2690) were obtained through liquid-assisted grinding and solvent evaporation with coformers functionalized with 4-pyridyl groups. The components form three- and four-component supramolecular assemblies sustained by a combination of (B)OH···Npyr hydrogen bonds and C–H···F interactions...

The dinuclear phenylboronic ester derived from pentaerythritol and trinuclear triphenylboroxine were combined with three diamine tectons, that is, 1,4-diazacyclohexane (pz), trans-1,4-diaminocyclohexane (1,4-chda), and 4-aminopyridine (4-apy), to generate supramolecular N→B bound assemblies and to enhance the knowledge concerning the factors govern...

The combination of one dipyridyl linker [1,2-di(4-pyridyl)ethylene (DPE), 1,2-di(4-pyridyl)ethane (DPEt), or 4,4′-azopyridine (DPA)] with two molecules of arylboronate ester 1 produced dinuclear Lewis-type N→B adducts that can act as acyclic host for polycyclic aromatic hydrocarbons (PAHs) in the solid state. Nine crystalline solids of composition...