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Crystal Structure And Hirshfeld Surface Analysis Of Cyclo-Tetrabromido-1k2br,3k2br-Tetrakis(Pi2-2-{[(Pyridin-2-Yl)Methyl]Amino}Ethane-1-Thiolato-Krystal Structure And Hirshfeld Surface Analysis Ofcyclo-Tetrabromido-1j2br,3j2br-Tetrakis(L2-2-{[(Pyridin-2-Yl)Methyl]Amino}Ethane-1-Thiolato-K3n,S:S)Tetramercury(Ii), I. D. Thomas, K. R. Kocher, J. A. Viehweg, Robert Pike, Deborah Bebout

Arts & Sciences Articles

The macrometallacyclic title compound, [Hg4Br4(C8H11N2S)4] or [((HgL2)(HgBr2))2] (1) where HL = 2-{[(pyridin-2-yl)meth­yl]amino}­ethane-1-thiol, was prepared and structurally characterized. The Hg2+ complex crystallizes in the P21/c space group. The centrosymmetric Hg4S4 metallacycle is constructed from metal ions with alternating distorted tetra­hedral Br2S2 and distorted seesaw N2S2 primary coordination environments with pendant pyridyl groups. The backfolded extended chair metallacycle conformation suggests inter­actions between each of the bis-chelated mercury atoms and Br atoms lying above and below the central Hg2S4 plane. Supra­molecular inter­actions in 1 include a fourfold aryl embrace and potential hydrogen bonds with bromine as the acceptor. Hirshfeld surface analysis indicates that …

Modeling Titan’S Atmosphere Through Investigation Of Low-Temperature Kinetics And Branching Of N (^2d) And C2h4 Towards Cyclic-2h-Azirine (C-Ch2nch), Ruby Neisser, Sophia Haile

Undergraduate Research Awards

Excerpt from paper: "Understanding the rate coefficients and branching of reactions in extraterrestrial atmospheres is of vital importance because it allows us to build a more complete picture of the overall chemical makeup and photochemical behavior in these alien environments. Gaining insight into these exotic reactions is crucial not only for understanding extraterrestrial environments, but also for providing a better understanding of reactions on Earth. The atmosphere of Titan, Saturn’s largest moon, is notably rich in nitrogen compounds and chemical reactions, which makes it an immensely important environment to study.1 Titan’s reducing atmosphere resembles that of early Earth (the first …

The Roles Of Tidal Marshes In The Estuarine Biochemical Processes: A Numerical Modeling Study, Xun Cai

VIMS Articles

Observations suggest that the existence of tidal marsh can alter the oxygen and nutrient dynamics in adjacent water bodies, but assessing the impacts of large tidal marshes on an estuary is challenging. In this study, we use a modeling approach to investigate the roles of tidal marshes on the estuarine biochemical processes. The marsh model, which simulates the ecological functions of marshes at seasonal and annual time-scales, is embedded inside an unstructured-grid three-dimensional hydrodynamic and eutrophication model (SCHISM-ICM). This modeling system simulates the growth and metabolism of the tidal marshes and links biological processes to nutrient dynamics in the water …

Comparison Of Electrochemical Polishing Treatments Between Phosphoric Acid And A Deep Eutectic Solvent For High-Purity Copper, Tarek M. Abdel-Fattah, Jon Derek Loftis

VIMS Articles

This study investigated and compared the acid-free electropolishing of copper with the state-of-the-art acidic electropolishing process. The acid-free medium used in this study is based on a deep eutectic solvent comprised of 2:1 ethylene glycol and choline chloride. The electrochemical study included voltammetry and chronoamperometry tests during the electropolishing process. The characterization techniques used were atomic force microscopy (AFM) and digital microscopy, and surface morphology comparisons summarized the electropolishing efficiency of phosphoric acid and acid-free deep eutectic solvent treatments for high-purity copper. Electropolishing copper with a deep eutectic solvent resulted in a mirror finish and a post-treatment surface that was …

Comparison Of Electropolishing Of Aluminum In A Deep Eutectic Medium And Acidic Electrolyte, Tarek M. Abdel-Fattah, Jon Derek Loftis

VIMS Articles

Research advances in electropolishing, with respect to the field of metalworking, have afforded significant improvements in the surface roughness and conductivity properties of aluminum polished surfaces in ways that machine polishing and simple chemical polishing cannot. The effects of a deep eutectic medium as an acid-free electrolyte were tested to determine the potential energy thresholds during electropolishing treatments based upon temperature, experiment duration, current, and voltage. Using voltammetry and chronoamperometry tests during electropolishing to supplement representative recordings via atomic force microscopy (AFM), surface morphology comparisons were performed regarding the electropolishing efficiency of phosphoric acid and acid-free ionic liquid treatments for …

Isotopes In The Estuary: Conception And Application Of Stable And Radioactive Carbon, Derek Detweiler

Reports

Grades: 9-12 Subjects: Chemistry | Environmental Science | Oceanography

In this interactive estuary-focused activity, students will examine stable and radioactive isotope data which provide information about the source and age of environmental samples such as plant and soil matter. Students will calculate average isotope ratios from five reference land types (forest, wetland, agriculture, industry, aquatic) and an unknown site within an estuary. Students will graph their calculated ratios and determine the land type that most impacts their estuary based on reference-to-unknown comparisons.

Asymmetric Hillslope Erosion Following Wildfire In Fourmile Canyon, Colorado, Edward R. Abrahams, James M. Kaste, William Ouimet, David P. Dethier

Arts & Sciences Articles

Infrequent, high-magnitude events cause a disproportionate amount of sediment transport on steep hillslopes, but few quantitative data are available that capture these processes. Here we study the influence of wildfire and hillslope aspect on soil erosion in Fourmile Canyon, Colorado. This region experienced the Fourmile Fire of 2010, strong summer convective storms in 2011 and 2012, and extreme flooding in September 2013. We sampled soils shortly after these events and use fallout radionuclides to trace erosion on polar- and equatorial-facing burned slopes and on a polar-facing unburned slope. Because these radionuclides are concentrated in the upper decimeter of soil, soil …

A Terbium Chlorobismuthate(Iii) Double Salt: Synthesis, Structure, And Photophysical Properties, John C. Ahern, Aaron D. Nicholas, Andrew W. Kelly, Benny Chan, Robert D. Pike, Howard Patterson

Arts & Sciences Articles

We report on the structure and luminescence of a double salt trivalent rare earth ion acceptor, Tb3+, with octahedral [BiCl6]3– donor clusters. The novel TbBiCl6·14H2O (1) was prepared from aqueous BiOCl and TbCl3·6H2O. The crystal structure of compound 1 exhibits isolated [BiCl6]3– and [Tb(OH2)8]3+ clusters. Luminescence data show energy transfer from octahedral chlorobismuthate(III) clusters to rare earth metal ions. Density Functional Theory (DFT) calculations show distinctly different emission pathways at high and low excitation energies.

Probing Molecular Dynamics With Hyperpolarized Ultrafast Laplace Nmr Using A Low-Field, Single-Sided Magnet, Jared N. King, Alfredo Fallorina, Justin Yu, Et Al., Tyler K. Meldrum

Arts & Sciences Articles

Laplace NMR (LNMR) offers deep insights on diffusional and rotational motion of molecules. The so-called “ultrafast” approach, based on spatial data encoding, enables one to carry out a multidimensional LNMR experiment in a single scan, providing from 10 to 1000-fold acceleration of the experiment. Here, we demonstrate the feasibility of ultrafast diffusion–T2 relaxation correlation (D–T2) measurements with a mobile, low-field, relatively low-cost, single-sided NMR magnet. We show that the method can probe a broad range of diffusion coefficients (at least from 10−8 to 10−12 m2 s−1) and reveal multiple components of fluids in heterogeneous …

Crystal Structure And Computational Analysis Of A Two-Dimensional Coordination Polymer, Bii3(Dppeo2)3/2, Andrew W. Kelly, Amelia M. Wheaton, Aaron D. Nicholas, Howard H. Patterson, Robert D. Pike

Arts & Sciences Articles

Catena-poly[fac-triiodobismuth(III)-tris-(µ-ethane-1,2-diylbis(diphenylphosphane oxide-κ2O,O′))], a 2-D sheet network of BiI3 was synthesized from BiI3 and ethane-1,2-diylbis(diphenylphosphane oxide) (DppeO2) in tetrahydrofuran. The crystal structure revealed a trigonal structure with three-fold symmetry at Bi. Bismuth centers show fac-BiI3O3 coordination, with Bi–I = 2.9416(2) Å and Bi–O = 2.4583(17) Å. The I–Bi–I and O–Bi–O angles (95.520(7)° and 79.04(6)°, respectively) indicate trigonal distortion in the Bi octahedron. Bridging DppeO2 ligands centered on inversion centers give rise to a 2-D sheet polymer. The 8.3 Å thick sheets consist of three layers in a sandwich structure. The outer layers are composed of phenyl rings and …

Tetragonal Diiodotetrapyridinedicopper(I): Structure, Luminescence, And Computational Modeling, Andrew W. Kelly, Joseph V. Handy, Aaron D. Nicholas, Et Al., Robert D. Pike

Arts & Sciences Articles

We report on a new crystal modification of (CuIPy2) n (Py = pyridine), a compound first reported by White et al. In contrast to White’s orthorhombic structure, which is comprised of rhomboid iodide-bridged dimers, Cu2I2Py4, our new tetragonal crystal structure in space group P41212 is disordered and can be interpreted as either iodide-bridged dimers or helical chains. To determine the structure type, variable temperature X-ray diffraction and luminescence measurements were carried out. The photoluminescence spectrum shows a distinct cluster-centered transition at high excitation energies which is consistent with the dimer structure. DFT and TD-DFT calculations were performed to explain …

Light-Induced Photochemical Changes In Copper(I) Thiocyanate Complexes Decorated With Halopyridines: Optical Memory Manifestation, Aaron D. Nicholas, Brooke M. Otten, Gerardo Ayala, Et Al., Robert D. Pike

Arts & Sciences Articles

We report on the photoluminescence of {CuSCN(3-XPy)2}n crystals (X = Br, Cl; Py = pyridine). Laser excitation at 266 nm for CuSCN(3-BrPy)2 at 78 K results in a decrease in the luminescence intensity with increasing irradiation time. Heating the sample to 298 K and recooling to 78 K results in recovery of the original luminescence intensity, hence manifesting an optical memory effect. Laser irradiation at longer or shorter wavelengths fails to produce a reduction in emission intensity. Interestingly, CuSCN(3-ClPy)2, despite being isomorphic, does not undergo emission intensity changes regardless of laser irradiation wavelength variation. Density functional theory (DFT) and …

Metal Substitution And Solvomorphism In Alkylthiolate-Bridged Zn3 And Hgzn2 Metal Clusters, Madeline R. Hallinger, Alison C. Gerhard, Mikhaila D. Ritz, Et Al., John C. Poutsma, Robert D. Pike

Arts & Sciences Articles

The impact of substituting Hg(II) for Zn(II) in a thiolate-bridged trinuclear cluster with parallels to a metallothionein metal cluster was investigated. A new solvomorph of [Zn(ZnL)2](ClO4)2 (1) (L = N-(2-pyridylmethyl)-N-(2-(ethylthiolato)-amine) and five solvomorphs of a new compound [Hg(ZnL)2](ClO4)2 (2) were characterized by single-crystal X-ray crystallography. The interplay of hydrogen bonding and aromatic-packing interactions in producing lamellar, 2D lamellar, and columnar arrangements of complex cations in the crystalline state is discussed. Both variable temperature proton nuclear magnetic resonance and electrospray ion-mass spectrometry (ESI-MS) suggest that the complex ions of 1 and 2 are the predominant solution species at …

Iodobismuthate(Iii) And Iodobismuthate(Iii)/Iodocuprate(I) Complexes With Organic Ligands, Andrew W. Kelly, Amelia M. Wheaton, Aaron D. Nicholas, Francis H. Barnes, Howard H. Patterson, Robert D. Pike

Arts & Sciences Articles

Iodobismuthate(III) and iodobismuthate(III)/cuprate(I) complexes with chelating and bridging organic ligands are structurally characterized, including the first iodobismuthate(III) metal–organic polymers. BiIII/CuI clusters show ligand binding at copper. Diffuse reflectance spectra show UV/Vis absorptions, and DFT calculations suggest MLCT and metal–halide centered transitions.

Numerical Simulations Of The Biogeochemical Impact Of Atmospheric Nitrogen Deposition On Surface Waters Of The Western North Atlantic, Pierre St-Laurent, Marjorie A.M. Friedrichs

Data

The impacts of atmospheric nitrogen deposition on the chlorophyll and nitrogen dynamics of surface waters in the western North Atlantic (25-45N, 65-80W) were examined with a biogeochemical ocean model forced with a regional atmospheric chemistry model. The model simulations cover the period 2004 to 2008 and are fully described in the following reference: St-Laurent, P., et al., Impacts of atmospheric nitrogen deposition on surface waters of the western North Atlantic mitigated by multiple feedbacks, J. Geophys. Res. Oceans, vol.122, doi:10.1002/2017jc013072.

Copper(I) Thiocyanate Networks With Aliphatic Sulfide Ligands, Gerardo Ayala, Robert D. Pike

Arts & Sciences Articles

A total of five new CuSCN-L compounds with alkyl sulfide ligands, L = methyl sulfide (Me2S), ethyl sulfide (Et2S), isopropyl sulfide (Pri2S) or tetrahydrothiophene (THT) have been prepared and characterized. X-ray crystal structures for four of the compounds were obtained. Two compounds were collected from solutions of CuSCN in Me2S: {[Cu(SCN)(Me2S)2]}n (1a) in the form of colorless blocks and (CuSCN)(Me2S) (1b) as a white powder. Neat mixtures of CuSCN in the other alkyl sulfide ligands yielded only one product each: {[Cu(SCN)(Et2S)]}n (2); {[Cu(SCN)(Pri2S)]}n (3); and {[Cu(SCN)(THT)2]}n (4). Crystals of 2 and 4 …

Copper(I) Oligomers And Polymers With Dicyanobenzene And Cyanopyridine Ligands, Mark K. Broderick, Congqi Yang, Robert D. Pike, Aaron Nicholas, Et Al.

Arts & Sciences Articles

The reaction of [Cu(MeCN)4]BF4 with o-, m-, or p-dicyanobenzene (DCB) or o-, m-, or p-cyanopyridine (CPy) in the presence of two equivalents of PPh3 produces DCB- or CPy-bridged copper(I) complexes. Cyclic dimers are formed for the ortho ligands, and zigzag polymers are formed using the para ligands. m-DCB produces a polymer, however m-CPy results in a cyclic trimer. Multiple lattice-bound solvates are formed upon crystallization of the o-DCB dimer from various solvents. A total of 11 X-ray crystal structures are reported for [Cun(PPh3)2n(bridge)n](BF4)n·(solvent): …

Alkali Metal Bismuth(Iii) Chloride Double Salts, Andrew W. Kelly, Aaron Nicholas, John C. Ahern, Benny Chan, Howard H. Patterson, Robert D. Pike

Arts & Sciences Articles

Evaporative co-crystallization of MCl (M = Na, K, Rb, Cs) with BiOCl in aqueous HCl produces double salts: MxBiyCl(x+3y)·zH2O. The sodium salt, Na2BiCl5·5H2O (monoclinic P21/c, a = 8.6983(7) Å, b = 21.7779(17) Å, c = 7.1831(6) Å, β = 103.0540(10)°, V = 1325.54(19) Å3, Z = 4) is composed of zigzag chains of μ2-Cl-cis-linked (BiCl5)n2n– chains. Edge-sharing chains of NaCln(OH2)6−n octahedra (n = 0, 2, 3) are linked through μ3-Cl to Bi. The potassium salt, K7Bi3Cl16 (trigonal R−3c, a = 12.7053(9) Å, …

Ultrafast Multidimensional Laplace Nmr Using A Single-Sided Magnet, Jared N. King, Vanessa J. Lee, Susanna Ahola, Ville-Veikko Telkki, Tyler Meldrum

Arts & Sciences Articles

Laplace NMR (LNMR) consists of relaxation and diffusion measurements providing detailed information about molecular motion and interaction. Here we demonstrate that ultrafast single- and multidimensional LNMR experiments, based on spatial encoding, are viable with low-field, single-sided magnets with an inhomogeneous magnetic field. This approach shortens the experiment time by one to two orders of magnitude relative to traditional experiments, and increases the sensitivity per unit time by a factor of three. The reduction of time required to collect multidimensional data opens significant prospects for mobile chemical analysis using NMR. Particularly tantalizing is future use of hyperpolarization to increase sensitivity by …

Molybdenum Complexes Of Chiral C2-Symmetric Picchxn-Type Ligands: Synthesis, Characterization, And Structural Studies, Rachel R. Bennov, David A. Berko, Samantha A. Burgess, John L. Dimeglio, Et Al., Robert D. Pike

Arts & Sciences Articles

A series of molybdenum complexes based on chiral C2-symmetric picchxn-type ligands (N4 ligands, defined as trans-N,N′-bis(heterocycl-2-ylmethyl)-1,2-diaminocyclohexanes) has been synthesized and characterized. Reported and novel picchxn-type ligands form (κ3-N4)Mo(CO)3, [(κ4-N4)Mo(NO)(CO)]PF6, and [(κ4-N4)Mo(NO)X]PF6 (X = Br, I) compounds. Multiple tridentate (κ3) and tetradentate (κ4) ligand configurations were observed, and the favored κ4 configuration was found to vary with N4 heterocycle identity. Heterocycle variation allowed for directed modification of the molybdenum electronic characteristics, but none of the studied {(κ4-N4)Mo(NO)}+ fragments was found to be a suitable …

Dual-Sensor Fluorescent Probes Of Surfactant-Induced Unfolding Of Human Serum Albumin, Christopher J. Abelt

Arts & Sciences Articles

Two extrinsic fluorescent probes, 3-(dimethylamino)-8,9,10,11-tetrahydro-7H-cyclohepta[a]naphthalen-7-one (1) and 7-(dimethylamino)-2,3-dihydrophenanthren-4(1H)-one (2), are used to probe the unfolding of human serum albumin by sodium dodecyl sulfate (SDS). These probes respond separately to the polarity and H-bond-donating ability of their surroundings. Competitive binding experiments show that fluorophore 1 binds to site I (domain IIA) and 2 binds to site II (domain IIIA). The local acidity of 1 in site I is out of the sensing range of 1, whereas the local acidity of 2 in site II is calculated to be nearly zero on Catalans solvent acidity index. Both probes show that the first …

Amine- And Sulfide-Sensing Copper(I) Iodide Films, James P. Killarney, Meaghan Mckinnon, Caitlin Murphy, Et Al., Robert D. Pike

Arts & Sciences Articles

Copper(I) iodide films were cast onto glass from solution. The CuI films absorb vapor-phase amine and sulfide molecules, producing a range of photoluminescent emission colors. Spectroscopic data suggest the presence of low energy CuI cluster-centered transitions.

Structure, Dynamics, And Photophysics In The Copper(I) Iodide–Tetrahydrothiophene System, Kylie M. Henline, Charles Wang, Robert D. Pike, John C. Ahern, Et Al.

Arts & Sciences Articles

Combination of CuI and tetrahydrothiophene (THT) in MeCN or neat THT produces various phases, depending upon experimental conditions. Green luminescent product (CuI)4(THT)2 (1) consists of Cu4I4 cubane units knit into a 3-D network by μ2-THT ligands. Dull yellow luminescent (CuI)10(THT)7(MeCN) (2) contains {[Cu4I4(THT)](μ2-THT)2(Cu2I2)(μ2-THT)2[Cu4I4(NCMe)]} “rungs” linked into 1-D ladders by pairs of μ2-THT ligands. Two molecular (CuI)4(THT)4 phases were found: orange luminescent 3a and yellow luminescent 3b. Triclinic 3b is the more stable phase at 25 °C, but it undergoes endothermic transformation to monoclinic 3a at 38 °C. Compound 3a transforms to a triclinic phase (3a′) that retains orange emission at …

Copper(I) Cyanide Networks With 1-Phenylpiperazine, Robert D. Pike, Thomas M. Dziura, Jordan C. Debutts, Courtney A. Murray, Et Al.

Arts & Sciences Articles

Aqueous reactions of copper(I) cyanide with 1-phenylpiperazine (PhPip) in the presence of KCN produce network compounds having CuCN:PhPip stoichiometries of 1:1, 3:2, and 4:1 depending on the mixing ratio used. In addition to these phases, hydrothermal synthesis yields a 5:3 network. Crystal structures of these four compounds are reported herein. The (CuCN)(PhPip) network (1) forms sheets consisting of Cu centers that coordinate all PhPip via NH only, and are linked together by μ3-cyano bridges. The (CuCN)3(PhPip)2 network (2) exists as a series of dual-chain ladders. All Cu centers are 3-coordinate and half of the PhPip ligands bridge pairs of chains …

Effect Of High Temperature Heat Treatments On The Quality Factor Of A Large-Grain Superconducting Radio-Frequency Niobium Cavity, P. Dhakal, G. Ciovati, G. R. Myneni, K. E. Gray, Et Al., Robert D. Pike

Arts & Sciences Articles

Large-grain Nb has become a viable alternative to fine-grain Nb for the fabrication of superconducting radio-frequency cavities. In this contribution we report the results from a heat treatment study of a large-grain 1.5 GHz single-cell cavity made of “medium purity” Nb. The baseline surface preparation prior to heat treatment consisted of standard buffered chemical polishing. The heat treatment in the range 800–1400°C was done in a newly designed vacuum induction furnace. Q0 values of the order of 2×1010 at 2.0 K and peak surface magnetic field (Bp) of 90 mT were achieved reproducibly. A Q0 value of (5±1)×1010 at 2.0 …

Local Solvent Acidities In Beta-Cyclodextrin Complexes With Prodan Derivatives, Christopher J. Abelt

Arts & Sciences Articles

The local solvent acidities (SA scale) of six 6-carbonyl-2-aminonaphthalene derivatives as beta-cyclodextrin complexes in water are determined through fluorescence quenching. The local polarities (E-T(N) scale) are determined through the shift of the emission center-of-mass. The apparent SA values reflect the solvent structure surrounding the guest's carbonyl group, whereas the apparent E-T(N) values reveal the net polarity of the entire guest molecule. Comparison of these values affords greater insight into the structures of the host-guest complexes. Derivatives 1 and 5 show unusually large acidities, indicative of highly exposed carbonyl groups. The remaining compounds give emission intensities pointing to shielded carbonyl groups. …

Carbonate-Templated Self-Assembly Of An Alkylthiolate-Bridged Cadmium Macrocycle, Wei La, Steven M. Berry, William P. Kaplan, Et Al., John C. Poutsma, Robert D. Pike, Deborah C. Bebout

Arts & Sciences Articles

In the presence of Cd(ClO4)2 and a base, a new mixed N,S-donor alkylthiolate ligand supported both carbonate formation from atmospheric CO2 and the self-assembly of a novel bicapped puckered (CdS)6 molecular wheel. The remarkable stability of the complex was demonstrated by slow intermolecular ligand exchange on the 2J(HH) and J(111/113Cd1H) time scales at elevated temperature. Both CO2 and the base were required to convert amorphous “CdLClO4” precipitated in the absence of air to the carbonate complex. The complex shares structural features with the ζ-carbonic anhydrase class associating cadmium(II) with the biogeochemical cycling of carbon and is the …

Atom Economical, One-Pot, Three-Reaction Cascade To Novel Tricyclic 2,4-Dihydro-1h-Benzo[F]Isochromenes, Robert J. Hinkle, Shane E. Lewis

Arts & Sciences Articles

A three-step domino reaction between 1-aryl-3-hexyne-2,6-diol derivatives and aldehydes is used to construct tricyclic 1,4-dihydro-2H-benzo[f]isochromenes. The cascade is initiated by BF₃·OEt₂ and involves alkynyl-Prins cyclization, Friedel–Crafts alkenylation, and dehydration/aromatization to create a new, central aromatic ring and eliminate 2 equiv. of water. Electron-donating substituents on the aryl ring of the 1-aryl-3-hexyne-2,6-diols significantly increase overall yields as do electron-rich aldehyde reaction partners. For 2,4-disubstituted 2H-benzo[f]isochromene products, diastereoselectivities in the alkynyl-Prins reaction are ∼1.4 : 1 in favor of the cis-diastereomer. The stereochemistry of one cis-product was verified by …

Bis(Tetra­Ethyl­Ammonium) Oxalate Dihydrate, Timothy J. Mcneese, Robert D. Pike

Arts & Sciences Articles

The title compound, 2C8H20N+ C2O4 22H2O, synthesized by neutralizing H2C2O42H2O with (C2H5)4NOH in a 1:2 molar ratio, is a deliquescent solid. The oxalate ion is nonplanar, with a dihedral angle between carboxylate groups of 64.37 (2). O—HO hydrogen bonds of moderate strength link the O atoms of the water molecules and the oxalate ions into rings parallel to the c axis. The rings exhibit the graph-set motif R4 4 (12). In addition, there are weak C—HO interactions in the crystal structure.

Carbonyl-Twisted 6-Acyl-2-Dialkylaminonaphthalenes As Solvent Acidity Sensors, Amy M. Green, Hannah R. Naughton, Zachariah B. Nealy, Robert D. Pike, Christopher J. Abelt

Arts & Sciences Articles

Derivatives of 2-propionyl-6-dimethylaminonaphthalene (PRODAN) with twisted carbonyl groups were investigated as highly responsive sensors of H-bond donating ability. The PRODAN derivative bearing a pivaloyl group (4) was prepared. The torsion angle between the carbonyl and naphthalene is 26° in the crystal. It shows solvatochromism that is similar to five other PRODAN derivatives (1–3, 5, 6). Twisted-carbonyl derivatives 3, 4, and 6 show strong fluorescence quenching in protic solvents. The order of magnitude of the quenching is linearly related to the H-bond donating ability of the solvent (SA) but not to other solvent properties. Binary mixtures of protic solvents show specific …