Graduate students Anna Yusov and Allie Dillon, along with Merck collaborators Mohammad T. Chaudhry, Justin A. Newman and Alfred Y. Lee, reported a comprehensive investigation aimed at benchmarking the utility of guanidinium organosulfonate (GS) host frameworks for structure determination of guest molecules for which X-ray structure determination can be elusive, such as liquids and olis. The team expanded on previous results through a head-to-head comparison of the GS method with adamantoid "molecular chaperones,” which have been reported to be useful hosts for structure determination. Inclusion compounds limited to only two GS hosts are characterized by low R1 values and Flack parameters, infrequent disorder of host and guest, manageable disorder when it does exist. The structure of some target molecules that were not included or resolved using the adamantoid chaperones were successfully included and resolved by the GS hosts, and vice versa. Of the 32 guests attempted by the GS method, 31 inclusion compounds afforded successful guest structure solutions, a 97% success rate. The GS hosts and adamantoid chaperones are complementary with respect to guest inclusion, arguing that both should be employed in the arsenal of methods for structure determination. Furthermore, the low cost of organosulfonate host components promises an accessible route to molecular structure determination for a wide range of users. The work was reported in ACS Materials Letters. Find the publication here.

In a demonstration of adaptive guest inclusion in a new aliphatic guanidinium monosulfonate hydrogen-bonded framework, graduate students Allie Dillon and Anna Yusov, along with NYU collaborators Krystyna M. Demkiw, K. A. Woerpel, and Merck collaborators Mohammad T. Chaudhry, Justin A. Newman ,and Alfred Y. Lee, discovered crystalline inclusion compounds based on a new aliphatic host – guanidinium cyclohexanemonosulfonate – which surprisingly exhibits four heretofore unobserved architectures, as described by the projection topologies of the organosulfonate residues above and below hydrogen-bonded guanidinium sulfonate sheets. The inclusion compounds adopt a layer motif consisting of the guanidinium sulfonate sheets interleaved with guest molecules, resembling a mille-feuille pastry. The aliphatic character of this remarkably simple host, combined with access to greater architectural diversity and adaptability, enables the host framework to accommodate a wide range of guests and promises to expand the utility of guanidinium organosulfonate hosts. The work was published in a special issue of Crystal Growth & Design dedicated to the renowned crystallographer Dr. Olga Kennard. Find the article here.

In a special issue dedicated to Martin Pope, a pioneer of organic electronics, graduate studnets Anna Yusov and Alexandra Dillon report that guanidinium organosulfonate (GS) hydrogen-bonded frameworks (HBFs) constructed from three different naphthalenesulfonates incorporate the electron acceptor tetracyanoquinodimethane (TCNQ) as a guest molecule, with framework architectures that reflect synergy between the persistent 2D hydrogen-bonded GS network and donor-acceptor interactions. The spectroscopic and computational results confirm weak charge-transfer interactions associated with the formation of mixed stacks containing naphthalene donors and TCNQ acceptors that are enforced by the GS framework, suggesting opportunities for the synthesis of new optoelectronic materials through a combination of molecular and crystal design. Find the article here.

Crystallization from the melt can allow the achievement of high driving force for crystallization accompanied by relatively slow growth, nucleation, and transformation rates, features that favor its use as an efficient polymorph screening method. Surprisingly, even though melt crystallization has a long history, it has been employed less often in the search for new polymorphs than solution crystallization. In a study of 21 well-characterized compounds with at least five ambient polymorphs, MDI investigators found that melt crystallization afforded more than half of the known polymorphs and in many cases revealed new polymorphs not detected by other screening methods. A statistical analysis revealed that polymorphs grown from the melt have a greater propensity for high Z′ values, which are not easily accessible by other crystallization protocols and are often not detectable by crystal structure prediction methods. Melt crystallization within nanopores (8–100 nm) performed for 19 of the 21 compounds mostly resulted in polymorphs that dominated crystallization from the bulk melt at similar temperatures. The total number of polymorphs observed in nanopores was less than that observed during crystallization from the bulk melt, however, and melt crystallization under confinement revealed new polymorphs not detected by other crystallization methods. Find the article here.

MDI investigators, including graduate students Fangyuan Dong, Samira Munkaila and Veronica Grebe, devised a synthetic strategy for fabricating colloidal particles with spatially segregated amine-functionalized lobes enables regioselective coating with gold to afford metallodielectric particles with a variety of shapes and lobe sizes. This approach can produce either dissymmetric dumbbell-shaped two-lobed Au-TPM particles (Au-T) or dissymmetric or symmetric three-lobed particles with gold coating on one (Au-T-T and T-Au-T) or two lobes (Au-T-Au). Dielectrophoretic (DEP) forces exerted by an AC field confined between two opposing electrodes generate aggregates ranging from 1D chains to 2D close-packed lattices, depending on the particle shape and lobe arrangement. The aggregate structures reflect the lowest energy configurations resulting from the induced dipole moments created in particle lobes within the confined electric field. Find the article here.

MDI investigators previously discovered that the efficacy of crystalline contact insecticides depends on the crystalline form (a.k.a. polymorphs). Polymorphism in contact insecticides, however, and its importance to efficacy, was largely unknown to the vector control community. Crystallographic characterization of contact insecticide solids needs to be systematic to identify more active solid forms. Here, the investigators report seven new crystal structures, mostly pyrethroid insecticides recommended by the WHO for indoor residual spraying, as well as a new form of a neonicotinoid insecticide. These results further highlight polymorphism in contact insecticides.

Impurities and intentionally introduced additives can exert significant influence on crystal growth, and they can play a critical role in crystallization processes. Additives can inhibit growth by binding to the edge of advancing steps. So-called “stopper” mechanisms, described by Cabrera-Vermilyea and Bliznakov, are regarded as the most effective mode of inhibition. Growth inhibition kinetic data, however, often do not fit these models, prompting the use of various corrections and numerical simulations. In a recently published article, MDI investigators describe approaches to more accurate modeling of kinetic data that reveal the limits of accurate and quantitative agreement with the aforementioned models. Kinetic data for crystal growth on the {0001} faces of L-cystine single crystals in the presence of the dimethylester of L-cystine, a proven growth inhibitor described as a “molecular imposter” or “tailor-made additive,” is simulated using a numerical model that incorporates chaotic distribution of stoppers over the crystal surface. A related analysis is included for potassium dihydrogen phosphate. Find the article here.

In a collaboration with the Woerpel group at NYU, graduate student Alexandra Dillon and Research Professor Tony Hu captured 2-chloropropiophenone in a hydrogen-bonded host framework generated from guanidinium and 4,4’-biphenyldisulfonate ions to produce a crystalline inclusion compound, which permitted the determination of the conformation of the 2-chloropropiophenone guest with single crystal X-ray diffraction. The observed conformation corroborated the stereoselectivity observed upon nucleophilic attack by allylmagnesium halide at the most accessible diastereoface of the lowest-energy conformations of the ketone.

Alex Shtukenberg, Bart Kahr and Mike Ward, along with Rutgers collaborators Longqin Hu and Amrik Sahota, summarize their findings on the unusual mechanisms of cystine crystal growth, growth inhibition by “molecular imposters,” and mouse model studies toward a therapy for the prevention of cystine kidney stones. See the article in Accounts of Chemical Research.

Two newly discovered University of Minnesota Videos on Hydrogen Bonding, by way of Travis Holman by way of Joel Bernstein. Click here for Video 1 and here for Video 2..

MDI Investigators discover seven new crystal polymorphs of imidacloprid, the world’s leading insecticide,, adding to two known forms. Anticipating that insect uptake of imidacloprid molecules would depend on the respective free energies of crystal polymorph surfaces, measurements of insect knockdown times for the metastable crystal forms were as much as nine times faster acting than the commercial form against Aedes, Anopheles, and Culex mosquitoes as well as Drosophila (fruit flies). Their results suggest that replacement of commercially available imidacloprid crystals (a.k.a. Form I) in space-spraying with any one of three new polymorphs, Forms IV, VI, IX, would suppress vector-borne disease transmission while reducing environmental exposure and harm to nontarget organisms. Find the article here.

Congrats to Anna Yusov and Allie Dillon for their perspective review article “Hydrogen bonded frameworks: smart materials used smartly” that appeared in the Royal Society of Chemistry journal Molecular Systems Design & Engineering! Find the article here

Graduate student Noalle Fellah and Alex Shtukenberg, joined by undergraduates Carolyn Zhang and Catherine Chen, Tony Hu and Bart Kahr reported the puzzling crystallization behaviors of nicotinamide and isonicotinamide, each forming eight polymorphs but differing in the number of polymorphs from solution or melt crystallization. Read the article here.

Congratulations to Drs. Xiaolong Zhu, Xiaodi Zhong and Noalle Fellah for outstanding final PhD defenses!

NYU Courant and Chemistry investigators report in the journal Soft Matter that autophoretic bimetallic nanorods propelled by hydrogen peroxide fuel preferentially orient upwards and ascend along inclined planes show when the swimmers are tail-heavy. Gravitaxis is facilitated by interactions with solid boundaries, allowing even ultraheavy microswimmers to climb nearly vertical surfaces. Theory and simulations show that the buoyancy or gravitational torque that tends to align the rods is reinforced by a fore-aft drag asymmetry induced by hydrodynamic interactions with the wall. Get the article here. Graphic courtesy of Jun Zhang/YanPeng Liu..

Graduate students Xiaodi Zhong, Hengyu Zhou, and coworkers reported in Chemical Communications the Eshelby twisting and untwisting of benzil nanocrystal in silico. The simulations revealed that nanrods with negative Burgers vectors increased the already present right-handed twisting, whereas dislocations with positive Burgers vectors drove the twisted structure back towards a straight configuration. The article can be found here.

Graduate students Noalle Fellah and Keke Zhang (Tianjin University), in collaboration with Dr. Vilmalí López-Mejías (University of Puerto Rico), report the polymorphic behavior of flufenamic acid under nanoscale confinement. Whereas previous reports have demonstrated that nanoconfinement can alter (thermodynamic) polymorph stability rankings, these results illustrate that nanoscale confinement can arrest and alter phase transformations kinetics such that otherwise hidden pathways can be observed. Find the article here.

Investigators from the NYU Molecular Design Institute and the University of Puerto Rico, Rio Piedras reported in the Proceedings of the National Academy of Sciences a new crystal polymorph of deltamethrin, a widely-used contact insecticide used for malaria prevention,, which is more than 10 times as effective against mosquitoes compared with the currently used version. The team included Jingxiang Yang, Bryan Erriah, Chunhua T. Hu, Ethan Reiter, Xiaolong Zhu, Mike Ward and Bart Kahr from NYU, and Vilmalí López-Mejías and Isis Paola Carmona-Sepúlveda from the UPR. Find the article here.

“Reinventing the Wheel” Illustrates digital art produced by Kenneth Jacob Ward (1982-2019), created during his tenure as Professorial Lecturer at American University in Washington DC. This art collection builds upon Kenneth’s passion to reveal the relationship between mathematics and art, hooking you with its beauty, symmetry and structure, and holding you with its humanity. Book available from blurb.com at cost here.

Graduate students Mingzhu Liu, Fangyuan Dong and Nicolle Jackson describe a synthetic strategy for the fabrication of multicomponent colloidal “molecules” with controllable complex morphologies and compositionally distinct lobes, enabling a scalable bulk synthesis of customized chiral colloidal particles with geometric and compositional chirality by a sequential seeded growth method. The synthetic protocol presents a versatile platform for constructing colloidal molecules with multiple components having customized shapes and functionalities, with the potential to impact the design of chromatic patchy particles, colloidal swimmers, and chiral optical materials, as well as informing programmable assembly. Find the article here.

Molecular Design Institute graduate students Fangyuan Dong, Mingzhu Liu and Veronica Grebe reported in Chemistry of Materials nineteen uniquely shaped anisotropic colloids that form ordered crystals under dielectrophoretic fields. The various particle shapes resulted in crystalline phases with p6m, cmm or p2 plane group symmetries, two plastic phases, and a disordered phase. The observations establish a relationship between particle shape and the resulting 2D structures, providing guidance for the design of 2D colloidal crystals. Link to the article here.

Undergraduate Sishuang Tang, graduate students Anna Yusov, Yuantao Li and Melissa Tan, visiting student Yunhui Hao, and Tony Hu teamed up to demonstrate that ROY, a compound known to form ten polymorphs with red, orange or yellow colors as a consequence of conformational flexibility, can be included in various guanidinium organosulfonate hydrogen-bonded frameworks that limit its conformational twisting out of plane. The publication was included in a special issue dedicated to Nobel Laureate Jean-Marie Lehn on the event of his 80th birthday. Link to the article here.

Postdoc Marcel Handke, graduate students Yang Wu and Yuantao Li, and Tony Hu discovered that the ubiquitous luminophore [Ru(bpy)3]2+ can be sequestered as a guest in an unusual guanidinium organosulfonate host framework architecture that guides the [Ru(bpy)3]2+ into 1D zigzag chains that suggest unique through-space energy transfer characteristics. Link to the article here.

Undergraduate members of the Ward lab, Sishuang Tang and Mengdi Qiu, celebrated their graduation from New York University in May 2020. Congrats!

Visiting student Keke Zhang (Tianjin University), Noalle Fellah, Alex Shtukenberg and Tony Hu report new polymorphs of the frontline tuberculosis drug isoniazid in CrystEngComm. Link to the article here.

Noalle Fellah, Alex Shtukenberg, and coworkers report in Crystal Growth & Design the structure of a new (fourth) polymorph of benzamide, a simple derivative of benzoic acid and a common intermediate of pharmaceutical compounds. The highly disordered form exhibits a bewildering crystallographic complexity due to 2D stacking faults and organizes like a mismatched stack of building blocks. Link to the article here.

Quentin Brosseau, Florencio Usabiaga, Enkeleida Lushi and Yang Wu report in Physical Review Letters exploring the behavior of micron-scale autophoretic Janus (Au/Pt) rods, with various (Au/Pt) length ratios, swimming near a wall in an imposed background flow. They find that the ability of the Au/Pt rods to robustly orient and move upstream, i.e., to rheotax, depends strongly on the Au/Pt ratio, which is easily tunable in synthesis. Link to the article here.