Detonation Velocity Measurement of a Hydrogen Peroxide Solvate of CL-20

The article of record as published may be found at https://doi.org/10.1002/prep.201800202Synthesis and development of new energetic molecules is a resource-intensive process, yielding materials with relatively unpredictable performance properties. Cocrystallization and crystalline solvate formation have been explored as possible routes towards developing new energetic materials that reduce the initial investment required for discovery and performance uncertainty because existing energetic molecules with known properties serve as the constituents. The formation of a hydrogen peroxide (HP) solvate of CL-20 was previously reported and has a density comparable to that of e-CL-20, the densest and most stable polymorph of CL-20. CL-20/HP produces a second crystalline form, which was unexpected given the high density of the original CL-20/HP solvate. Both forms were predicted to have improved detonation performance relative to that of e-CL-20. In this work, the detonation velocity of a solvate of CL-20/HP is measured and compared to that of CL-20...This material is based upon work supported by the U. S. Army Research Laboratory and the U. S. Army Research Office under contract/grant number W911NF-13-1-0387.This material is based upon work supported by the U. S. Army Research Laboratory and the U. S. Army Research Office under contract/grant number W911NF-13-1-0387

Chargeâ Transport Properties of F6TNAPâ Based Chargeâ Transfer Cocrystals

The crystal structures of the chargeâ transfer (CT) cocrystals formed by the Ï â electron acceptor 1,3,4,5,7,8â hexafluoroâ 11,11,12,12â tetracyanonaphthoâ 2,6â quinodimethane (F6TNAP) with the planar Ï â electronâ donor molecules triphenylene (TP), benzo[b]benzo[4,5]thieno[2,3â d]thiophene (BTBT), benzo[1,2â b:4,5â bâ ²]dithiophene (BDT), pyrene (PY), anthracene (ANT), and carbazole (CBZ) have been determined using singleâ crystal Xâ ray diffraction (SCXRD), along with those of two polymorphs of F6TNAP. All six cocrystals exhibit 1:1 donor/acceptor stoichiometry and adopt mixedâ stacking motifs. Cocrystals based on BTBT and CBZ Ï â electron donor molecules exhibit brickwork packing, while the other four CT cocrystals show herringboneâ type crystal packing. Infrared spectroscopy, molecular geometries determined by SCXRD, and electronic structure calculations indicate that the extent of groundâ state CT in each cocrystal is small. Density functional theory calculations predict large conduction bandwidths and, consequently, low effective masses for electrons for all six CT cocrystals, while the TPâ , BDTâ , and PYâ based cocrystals are also predicted to have large valence bandwidths and low effective masses for holes. Chargeâ carrier mobility values are obtained from spaceâ charge limited current (SCLC) measurements and fieldâ effect transistor measurements, with values exceeding 1 cm2 Vâ 1 s1 being estimated from SCLC measurements for BTBT:F6TNAP and CBZ:F6TNAP cocrystals.Structural, electronic band structure, and electrical properties of a series of chargeâ transfer cocrystals based on F6TNAP and six planar donors are presented. Density functional theory calculations afford large conduction bandwidths and low effective masses for all six cocrystals. A few cocrystals exhibit chargeâ carrier mobilities in excess of 1 cm2 Vâ 1 sâ 1, as estimated from spaceâ charge limited current measurements.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153248/1/adfm201904858-sup-0001-S1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153248/2/adfm201904858.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153248/3/adfm201904858_am.pd

Halogen Bonding Propensity in Solution: Direct Observation and Computational Prediction

Halogen‐bonded complexes are often designed by consideration of electrostatic potential (ESP) predictions. ESP predictions do not capture the myriad variables associated with halogen bond (XB) donors and acceptors; thus, binding interaction cannot be quantitatively predicted. Here, a discrepancy between predictions based on ESP energy difference (ΔVs) and computed gas phase binding energy (ΔEbind) motivated the experimental determination of the relative strength of halogen bonding interactions in solution by Raman spectroscopic observation of complexes formed from interacting five iodobenzene‐derived XB donors and four pyridine XB acceptors. Evaluation of ΔEbind coupled with absolutely‐localized molecular orbital energy decomposition analysis (ALMO‐EDA) deconvolutes halogen bonding energy contributions and reveals a prominent role for charge transfer (CT) interactions. Raman spectra reveal ΔEbind accurately predicts stronger interactions within iodopentafluorobenzene (IPFB) complexes than with 1‐iodo‐3,5‐dinitrobenzene (IDNB) complexes even though IPFB has similar electrostatics to IDNB and contains a smaller σ‐hole.Strongly activated halogen bond donors give rise to observable bound and unbound states in Raman spectroscopy when paired with good halogen bond acceptors. The two strongest halogen bond donors examined have almost identical electrostatic potentials, but differ vastly in theoretical binding affinity and experimental halogen bonding strength. The energy terms giving rise to this behavior are elucidated by energy decomposition analysis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/171007/1/chem202102522.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/171007/2/chem202102522_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/171007/3/chem202102522-sup-0001-misc_information.pd

Two‐Dimensional Crystals from Reduced Symmetry Analogues of Trimesic Acid

The two‐dimensional assembly of multicarboxylated arenes is explored at the liquid–graphite interface using scanning tunneling microscopy. Symmetry variations were introduced via phenylene spacer addition and the influence of these perturbations on the formation of hydrogen‐bonded motifs from an alkanoic acid solvent is observed. This work demonstrates the importance of symmetry in 2D crystal formation and draws possible links of this behavior to prediction of coordination modes in three‐dimensional coordination polymers.Crystal clear: 2D assemblies of a series of five reduced symmetry multicarboxylated molecules (such as depicted) related to trimesic acid, a prototypical high symmetry adsorbate, through the addition of phenylene spacers, are explored at the liquid–graphite interface using scanning tunneling microscopy. The 2D assembly behaviors of these multicarboxylate molecules mirror their coordination modes in 3D coordination polymers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110860/1/chem_201406332_sm_miscellaneous_information.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/110860/2/5954_ftp.pd

Functional Group Effects on the Enthalpy of Adsorption for Self-Assembly at the Solution/Graphite Interface

The thermodynamics of self-assembly have long been explored by either experimental or theoretical investigations which are often unable to account for all the factors influencing the assembly process. This work interrogates the thermodynamics of self-assembly at a liquid/solid interface by measuring the enthalpy of adsorption encompassing analyte–analyte, analyte–solvent, analyte–substrate, and solvent–substrate interactions. Comparison of the experimental data with computed lattice energies for the relevant monolayers across a series of aliphatic analytes reveals similar ordering within the series, with the exceptions of the fatty acid and bromoalkane adsorbates. Such a discrepancy could arise when the lattice energies do not account for important interactions, such as analyte–analyte interactions in solution. Flow microcalorimetry provides a uniquely inclusive view of the thermodynamic events relevant to self-assembly at the liquid/solid interface

Evaluation of the Appropriate Use of Characterization Methods for Differentiation between Cocrystals and Physical Mixtures in the Context of Energetic Materials

Cocrystallization is an attractive method by which to tune the physical properties of energetic materials. However, in the absence of single-crystal X-ray diffraction (SC-XRD), rigorously characterizing the results of cocrystallization attempts can be difficult. Specifically, differentiating between physical mixtures and true cocrystalline materials is challenging due to the propensity for energetic molecules to form solvates and/or polymorphs. The suitability and limitations of morphological analysis, vibrational (infrared and Raman) spectroscopy, and powder XRD are discussed within the context of six previously published materials claimed to be cocrystals but lacking SC-XRD structures. It was found that in all six cases the data originally published are consistent with crystallization of physical mixtures of the two starting components; in three of these cases the crystallization procedures were reproduced and the characterization data support the presence of physical mixtures. Data interpretation is convoluted by the presence of solvent/solvate formation or polymorphism in all six cases illustrating the ubiquity of the challenges faced in energetic cocrystal discovery

MOFâ 5â Polystyrene: Direct Production from Monomer, Improved Hydrolytic Stability, and Unique Guest Adsorption

An unprecedented mode of reactivity of Zn4Oâ based metalâ organic frameworks (MOFs) offers a straightforward and powerful approach to polymerâ hybridized porous solids. The concept is illustrated with the production of MOFâ 5â polystyrene wherein polystyrene is grafted and uniformly distributed throughout MOFâ 5 crystals after heating in pure styrene for 4â 24â h. The surface area and polystyrene content of the material can be fineâ tuned by controlling the duration of heating styrene in the presence of MOFâ 5. Polystyrene grafting significantly alters the physical and chemical properties of pristine MOFâ 5, which is evident from the unique guest adsorption properties (solvatochromic dye uptake and improved CO2 capacity) as well as the dramatically improved hydrolytic stability of composite. Based on the fact that MOFâ 5 is the best studied member of the structure class, and has been produced at scale by industry, these findings can be directly leveraged for a range of current applications.MOFs packed with polystyrene: An unprecedented mode of reactivity of one of the best studied metalâ organic frameworks, MOFâ 5, offers a powerful approach to polymerâ hybridized porous solids. A MOFâ 5â polystyrene (MOFâ 5â PS) composite was directly produced from the monomer styrene. In the MOFâ 5â PS composites, polystyrene is grafted and uniformly distributed throughout, which leads to enhanced hydrolytic stability and unique guest adsorption.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134282/1/anie201606926_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134282/2/anie201606926-sup-0001-misc_information.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134282/3/anie201606926.pd

MOFâ 5â Polystyrene: Direct Production from Monomer, Improved Hydrolytic Stability, and Unique Guest Adsorption

An unprecedented mode of reactivity of Zn4Oâ based metalâ organic frameworks (MOFs) offers a straightforward and powerful approach to polymerâ hybridized porous solids. The concept is illustrated with the production of MOFâ 5â polystyrene wherein polystyrene is grafted and uniformly distributed throughout MOFâ 5 crystals after heating in pure styrene for 4â 24â h. The surface area and polystyrene content of the material can be fineâ tuned by controlling the duration of heating styrene in the presence of MOFâ 5. Polystyrene grafting significantly alters the physical and chemical properties of pristine MOFâ 5, which is evident from the unique guest adsorption properties (solvatochromic dye uptake and improved CO2 capacity) as well as the dramatically improved hydrolytic stability of composite. Based on the fact that MOFâ 5 is the best studied member of the structure class, and has been produced at scale by industry, these findings can be directly leveraged for a range of current applications.Mit Polystyrol gepackte MOFs: Eine bisher unbekannte Reaktivität eines der am besten untersuchten Metallâ organischen Gerüstmaterialien, MOFâ 5, bietet Zugang zu polymerhybridisierten porösen Festkörpern. Ein MOFâ 5â Polystyrol(MOFâ 5â PS)â Komposit wurde direkt aus dem Monomer Styrol hergestellt. Das Polystyrol ist im MOFâ 5â PSâ Gerüst einheitlich verteilt und bewirkt eine erhöhte Hydrolysestabilität.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134159/1/ange201606926.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134159/2/ange201606926-sup-0001-misc_information.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134159/3/ange201606926_am.pd