Chemistry Commons^™

Fast Excited-State Deactivation In N(5)-Ethyl-4a-Hydroxyflavin Pseudobase, Dapeng Zhou, Ekaterina Mirzakulova, Renat Khatmullin, Igor Schapiro, Massimo Olivucci, Ksenija D. Glusac

Chemistry Faculty Publications

We present a study of the excited-state behavior of N(5)-ethyl-4a-hydroxyflavin (Et-FlOH), a model compound for bacterial bioluminescence. Using femtosecond pump-probe spectroscopy, we found that the Et-FlOH excited state exhibits multiexponential dynamics, with the dominant decay component having a 0.5 ps lifetime. Several possible mechanisms for fast excited-state decay in Et-FlOH were considered: (i) excited-state deprotonation of the -OH proton, (ii) thermal deactivation via (1)n,pi* -> (1)pi,pi* conical intersection, and (iii) excited-state release of OH(-) ion. These mechanisms were excluded based on transient absorption studies of two model compounds (N(5)-ethyl-4a-methoxyflavin, Et-FlOMe, and N(5)-ethyl-flavinium ion, Et-Fl(+)) and based on the results of …

Maxwell's Equations, Part Ii, David W. Ball

Chemistry Faculty Publications

This is the second part of a multi-part production on Maxwell’s equations of electromagnetism. The ultimate goal is a definitive explanation of these four equations; readers will be left to judge how definitive it is. A note: for certain reasons, figures are being numbered sequentially throughout this series, which is why the first figure in this column is numbered 8. I hope this does not cause confusion. Another note: this is going to get a bit mathematical. It can’t be helped: models of the physical universe, like Newton’s second law F = ma, are based in math. So are Maxwell’s …

Physico-Chemical And Microbiological Parameters In The Deterioration Of Virgin Coconut Oil, Ian Ken D. Dimzon, Melodina F. Valde, Jaclyn Elizabeth R. Santos, Mark Joseph Garrovillas, Henson M. Dejarme, Jo Margarette W. Remollo, Fabian M. Dayrit

Chemistry Faculty Publications

The deterioration of virgin coconut oil (VCO) due to physico-chemical oxidation and hydrolysis and microbiological processes was studied. The physico-chemical oxidation of VCO in the air at room temperature was negligible. Oxidation of VCO was observed only in the presence of air, UV radiation, ferric ion (Fe3+), and high free fatty acid (FFA) content. Chemical hydrolysis was performed at varying moisture levels and temperatures. The rate of hydrolysis to produce FFAs was measured using 31P NMR under conditions of saturated water (0.22%) and 80°C was found to be 0.066 µmol/g-hr (expressed as lauric acid). At 0.084% moisture and 80°C, the …

The Exonuclease Activity Of Hpmc2 Is Required For Transcriptional Regulation Of The Qr Gene And Repair Of Estrogen-Induced Abasic Sites, N. Krishnamurthy, C. R. Ngam, Anthony J. Berdis, M. M. Montano

Chemistry Faculty Publications

We have previously reported that the expression of antioxidative stress enzymes is upregulated by trans-hydroxytamoxifen (TOT) in breast epithelial cell lines providing protection against estrogen-induced DNA damage. This regulation involves Estrogen Receptor β (ERβ) recruitment to the Electrophile Response Element (EpRE) and a novel protein, human homolog of Xenopus gene which Prevents Mitotic Catastrophe (hPMC2). We have also demonstrated that ERβ and hPMC2 are required for TOT-dependent recruitment of poly (ADP-ribose) polymerase 1 (PARP-1) and Topoisomerase IIβ (Topo IIβ) to the EpRE. Sequence analysis reveals that the C-terminus of hPMC2 encodes a putative exonuclease domain. Using in vitro kinetic assays, …

Profiling Sterols In Cerebrotendinous Xanthomatosis: Utility Of Girard Derivatization And High Resolution Exact Mass Lc-Esi-Msn Analysis, Andrea E. Debarber, Yana Sandlers, Anuradha S. Pappu, Louise S. Merkens, P. Barton Duell, Steven R. Lear, Sandra K. Erickson, Robert D. Steiner

Chemistry Faculty Publications

In this study we profile free 3-oxo sterols present in plasma from patients affected with the neurodegenerative disorder of sterol and bile acid metabolism cerebrotendinous xanthomatosis (CTX), utilizing a combination of charge-tagging and LC-ESI-MSn performed with an LTQ-Orbitrap Discovery instrument. In addition, we profile sterols in plasma from 24-month-old cyp27A1 gene knockout mice lacking the enzyme defective in CTX. Charge-tagging was accomplished by reaction with cationic Girard's P (GP) reagent 1-(carboxymethyl) pyridinium chloride hydrazide, an approach uniquely suited to studying the 3-oxo sterols that accumulate in CTX, as Girard's reagent reacts with the sterol oxo moiety to form charged hydrazone …

Probing Ground-State Single-Electron Self-Exchange Across A Molecule−Metal Interface, Yuanmin Wang, Papatya C. Sevinc, Yufan He, H. Peter Lu

Chemistry Faculty Publications

We have probed single-molecule redox reaction dynamics of hemin (chloride) adsorbed on Ag nanoparticle surfaces by single-molecule surface-enhanced Raman spectroscopy (SMSERS) combined with spectroelectrochemistry. Redox reaction at the molecule/Ag interface is identified and probed by the prominent fluctuations of the Raman frequency of a specific vibrational mode, nu(4), which is a typical marker of the redox state of the iron center in a hemin molecule. On the basis of the autocorrelation and cross-correlation analysis of the single-molecule Raman spectral trajectories and the control measurements of single-molecule spectroelectochemistry and electrochemical STM, we suggest that the single-molecule redox reaction dynamics at the …

Epistatic Roles For Pseudomonas Aeruginosa Muts And Dinb (Dna Pol Iv) In Coping With Reactive Oxygen Species-Induced Dna Damage, Laurie H. Sanders, Babho Devadoss, Geraldine V. Raja, Jaime O'Connor, Shengchang Su, Daniel J. Wozniak, Daniel J. Hassett, Anthony J. Berdis, Mark D. Sutton

Chemistry Faculty Publications

Pseudomonas aeruginosa is especially adept at colonizing the airways of individuals afflicted with the autosomal recessive disease cystic fibrosis (CF). CF patients suffer from chronic airway inflammation, which contributes to lung deterioration. Once established in the airways, P. aeruginosa continuously adapts to the changing environment, in part through acquisition of beneficial mutations via a process termed pathoadaptation. MutS and DinB are proposed to play opposing roles in P. aeruginosa pathoadaptation: MutS acts in replication-coupled mismatch repair, which acts to limit spontaneous mutations; in contrast, DinB (DNA polymerase IV) catalyzes error-prone bypass of DNA lesions, contributing to mutations. As part of …

The Low Resolution Structure Of Apoa1 In Spherical High Density Lipoprotein Revealed By Small Angle Neutron Scattering, Zhiping Wu, Valentin Gogonea, Xavier Lee, Roland P. May, Vitaliy Pipich, Matthew A. Wagner, Arundhati Undurti, Thomas C. Tallant, Camelia Baleanu Gogonea, Francesca Charlton, Alexander I. Ioffe, Joseph A. Didonato, Kerry Anne Rye, Stanley L. Hazen

Chemistry Faculty Publications

Spherical high density lipoprotein (sHDL), a key player in reverse cholesterol transport and the most abundant form of HDL, is associated with cardiovascular diseases. Small angle neutron scattering with contrast variation was used to determine the solution structure of protein and lipid components of reconstituted sHDL. Apolipoprotein A1, the major protein of sHDL, forms a hollow structure that cradles a central compact lipid core. Three apoA1 chains are arranged within the low resolution structure of the protein component as one of three possible global architectures: (i) a helical dimer with a hairpin (HdHp), (ii) three hairpins (3Hp), or (iii) an …

Engineering Cooperative Tecto-Rna Complexes Having Programmable Stoichiometries, Neocles B. Leontis, Irina V. Novikova, Bachar H. Hassan, Marina G. Mirzoyan

Chemistry Faculty Publications

High affinity and specificity RNA-RNA binding interfaces can be constructed by combining pairs of GNRA loop/loop-receptor interaction motifs. These interactions can be fused using flexible four-way junction motifs to create divalent, self-assembling scaffolding units ('tecto-RNA') that have favorable properties for nanomedicine and other applications. We describe the design and directed assembly of tecto-RNA units ranging from closed, cooperatively assembling ring-shaped complexes of programmable stoichiometries (dimers, trimers and tetramers) to open multimeric structures. The novelty of this work is that tuning of the stoichiometries of self-assembled complexes is achieved by precise positioning of the interaction motifs in the monomer units rather …

Suppression Of The Plasmon Resonance In Au/Cds Colloidal Nanocomposites, Elena Khon, Andrey Mereshchenko, Alexander N. Tarnovsky, Krishna Acharya, Anna Klinkova, Nishshanka N. Hewa-Kasakarage, Ian Nemitz, Mikhail Zamkov

Chemistry Faculty Publications

The nature of exciton-plasmon interactions in Au-tipped CdS nanorods has been investigated using femtosecond transient absorption spectroscopy. The study demonstrates that the key optoelectronic properties of composite heterostructures comprising electrically coupled metal and semiconductor domains are substantially different from those observed in systems with weak interdomain coupling. In particular, strongly coupled nanocomposites promote mixing of electronic states at semiconductor-metal domain interfaces, which causes a significant suppression of both plasmon and exciton excitations of carriers.

Maxwell's Equations, Part I: History, David W. Ball

Chemistry Faculty Publications

Maxwell’s equations for electromagnetism are the fundamental understanding of how light behaves. There are various versions, depending on whether there is vacuum, a charge present, matter present, the system is relativistic or quantum, or are written in terms of differential or integral calculus. Here, I inaugurate a multi-part series on a discussion of each of Maxwell’s equations. The goal is for this series to become the definitive explanation of these rules (I know, a heady goal!). I trust readers will let me know if I succeed. In this first installment, we will discuss a little bit of historical development as …

Simultaneous Spectroscopic And Topographic Near-Field Imaging Of Tio2 Single Surface States And Interfacial Electronic Coupling, Papatya C. Sevinc, Xiao Wang, Yuanmin Wang, Dai Zhang, Alfred J. Meixner, H. Peter Lu

Chemistry Faculty Publications

We have probed single surface states and the involved interfacial charge transfer coupling on the TiO2 surface using confocal as well as tip-enhanced near-field topographic-spectroscopic imaging analysis on a niobium-doped rutile TiO2(110) surface. The confocal images excited with a radially polarized donut mode render ring-shaped excitation patterns typical for quantum systems with two perpendicular transition dipole moments. The tip-enhanced near-field optical images of single surface states are visualized by the strong exciton plasmon-polariton coupling localized at the subdomain boundaries with a spatial resolution of similar to 15 nm (far beyond the optical diffraction limit). We suggest that the abundant surface …

A Sodium Salt Of The Dimer Of Boronoterephthalic Acid Anhydride, Scott Simmons, Albert Fratini, Vladimir Benin

Chemistry Faculty Publications

The title compound, sodium bis­(6-carb­oxy-1-hy­droxy-3-oxo-1,3-dihydro-2,1-benzoxaborol-1-yl)oxidanium, Na+·C16H15B2O13-, was prepared in two steps from 2-bromo-p-xylene. Its crystal structure was determined at 140 K and has triclinic (P) symmetry. The compound presents a unique structural motif, including two units of the cyclic anhydride of boronoterephthalic acid, joined by a protonated, and thereby trivalent, oxonium center. Association in the crystal is realized by complementary hydrogen bonding of the carboxyl groups, as well as by coordination of the sodium cations to the oxygen centers on the five-membered rings.

Theoretical Investigation Of A Reported Antibiotic From The 'Miracle Tree' Moringa Oleifera, Michael Horwath, Vladimir Benin

Chemistry Faculty Publications

Moringa oleifera, sometimes called the “Miracle Tree,” has received international attention for its potential to improve health in impoverished tropical areas. In addition to high vitamin content in the leaves and pods, the tree contains compounds with antioxidant and antibacterial properties. This study focused on the theoretical investigation of the suggested structure of one antibacterial compound, “pterygospermin,” whose existence was proposed after some studies of the roots of M. oleifera. The structure of pterygospermin was first proposed by a research group working in the 1950s, but later studies have not found evidence of this compound and have instead …

Homozygous Mutation In Samhd1 Gene Causes Cerebral Vasculopathy And Early Onset Stroke, Baozhong Xin, Stephen Jones, Erik G. Puffenberger, Claas Hinze, Alicia Bright, Haiyan Tan, Aimin Zhou, Guiyun Wu, Jilda Vargus Adams, Dimitris Agamanolis, Heng Wang

Chemistry Faculty Publications

We describe an autosomal recessive condition characterized with cerebral vasculopathy and early onset of stroke in 14 individuals in Old Order Amish. The phenotype of the condition was highly heterogeneous, ranging from severe developmental disability to normal schooling. Cerebral vasculopathy was a major hallmark of the condition with a common theme of multifocal stenoses and aneurysms in large arteries, accompanied by chronic ischemic changes, moyamoya morphology, and evidence of prior acute infarction and hemorrhage. Early signs of the disease included mild intrauterine growth restriction, infantile hypotonia, and irritability, followed by failure to thrive and short stature. Acrocyanosis, Raynaud’s phenomenon, chilblain …

Quantifying The Energetic Contributions Of Desolvation And Π-Electron Density During Translesion Dna Synthesis, Edward A. Motea, Irene Lee, Anthony J. Berdis

Chemistry Faculty Publications

This report examines the molecular mechanism by which high-fidelity DNA polymerases select nucleotides during the replication of an abasic site, a non-instructional DNA lesion. This was accomplished by synthesizing several unique 5-substituted indolyl 2′-deoxyribose triphosphates and defining their kinetic parameters for incorporation opposite an abasic site to interrogate the contributions of π-electron density and solvation energies. In general, the Kd, app values for hydrophobic non-natural nucleotides are ∼10-fold lower than those measured for isosteric hydrophilic analogs. In addition, kpol values for nucleotides that contain less π-electron densities are slower than isosteric analogs possessing higher degrees of π-electron density. The differences …

The Ultrafast Photoisomerizations Of Rhodopsin And Bathorhodopsin Are Modulated By Bond Length Alternation And Hoop Driven Electronic Effects, Igor Schapiro, Mikhail Nikolaevich Ryazantsev, Luis Manuel Frutos, Nicolas Ferre, Roland Lindh, Massimo Olivucci

Chemistry Faculty Publications

Rhodopsin (Rh) and bathorhodopsin (bathoRh) quantum-mechanics/molecular-mechanics models based on ab initio multiconfigurational wave functions are employed to look at the light induced pi-bond breaking and reconstitution occurring during the Rh -> bathoRh and bathoRh -> Rh isomerizations. More specifically, semiclassical trajectory computations are used to compare the excited (S-1) and ground (S-0) state dynamics characterizing the opposite steps of the Rh/bathoRh photochromic cycle during the first 200 fs following photoexcitation. We show that the information contained in these data provide an unprecedented insight into the sub-picosecond pi-bond reconstitution process which is at the basis of the reactivity of the protein …

Growth Factor Signaling Enhances Aromatase Activity Of Breast Cancer Cells Via Post-Transcriptional Mechanisms, Bin Su, Cynthie Wong, Yanyan Hong, Shiuan Chen

Chemistry Faculty Publications

It has been demonstrated that growth factors produced by breast cancer cells stimulate aromatase expression in both breast cancer and adjacent adipose fibroblasts and stromal cells. However, whether these growth factors affect aromatase activity by other mechanisms still remain unclear. In the current study, MCF-7aro and T47Daro aromatase transfected breast carcinoma cells were used to explore the mechanisms of post-transcriptional regulation of aromatase activity by growth factor pathways. Our study reveals that PI3K/Akt and MAPK inhibitors suppressed aromatase activity in MCF-7aro cells. However, PI3K/Akt pathway inhibitors stimulated aromatase activity in T47Daro cells. This is due to enhanced MAPK phosphorylation as …

The Tyranny Of The Vital Few: The Pareto Principle In Language Design, Victor L. Winter, James L. Perry, Harvey Siy, Satish Srinivasan, Ben Farkas, James Mccoy

Chemistry Faculty Publications

Modern high-level programming languages often contain constructs whose semantics are non-trivial. In practice how- ever, software developers generally restrict the use of such constructs to settings in which their semantics is simple (programmers use language constructs in ways they understand and can reason about). As a result, when developing tools for analyzing and manipulating software, a disproportionate amount of effort ends up being spent developing capabilities needed to analyze constructs in settings that are infrequently used. This paper takes the position that such distinctions between theory and practice are an important measure o f the analyzability of a language.

Crystallization And Preliminary X-Ray Crystallographic Analysis Of Ligand-Free And Arginine-Bound Forms Of Thermotoga Maritima Arginine-Binding Protein, Alessia Ruggiero, Jonathan D. Dattelbaum, Anna Pennacchio, Luisa Iozzion, Maria Staiano, Matthew S. Luchansky, Bryan S. Der, Rita Berisio, Sabato D'Auria, Luigi Vitagliano

Chemistry Faculty Publications

The arginine-binding protein from Thermotoga maritima (TmArgBP) is an arginine-binding component of the ATP-binding cassette (ABC) transport system in this hyperthermophilic bacterium. This protein is endowed with an extraordinary stability towards thermal and chemical denaturation. Its structural characterization may provide useful insights for the clarification of structure– stability relationships and for the design of new biosensors. Crystallization trials were set up for both arginine-bound and ligand-free forms of TmArgBP and crystals suitable for crystallographic investigations were obtained for both forms. Ordered crystals of the arginine adduct of TmArgBP could only be obtained by using the detergent LDAO as an additive …

Quality Characteristics Of Virgin Coconut Oil:Comparisons With Refined Coconut Oil, Fabian M. Dayrit, Ian Ken D. Dimzon, Melodina F. Valde, Jaclyn Elizabeth R. Santos, Mark Joseph Garrovillas, Blanca J. Villarino

Chemistry Faculty Publications

Virgin coconut oil (VCO) is a vegetable oil that is extracted from fresh coconut meat and is processed using only physical and other natural means. VCO was compared to refined, bleached, and deodorized coconut oil (RCO) using standard quality parameters, 31 P nuclear magnetic resonance (NMR) spectroscopy, and headspace solid-phase micro - extraction/gas chromatography mass spectrometry (SPME/GCMS). VCO tends to have higher free fatty acids (FFAs), moisture, and volatile matter and lower peroxide value than RCO. However, the range of values overlap and no single standard parameter alone can be 31 used to differentiate VCO from RCO. Using 31P NMR, …

Rational Design Of Etchants For Electroless Porous Silicon Formation, Kurt Kolasinski, J W. Gogola

Chemistry Faculty Publications

From fundamental considerations of the surface chemistry of Si etching in fluoride solutions as well as pore formation and propagation, we develop a mechanistic understanding of what must be known for rational development of etchants: (1) an acidic fluoride solution because the presence of OH- promotes step flow etching, (2) sufficiently high fluoride concentration compared to the oxidant concentration, (3) the oxidant must be able to inject holes into the Si valance band at a sufficient rate, hence E degrees > similar to 0.7 V is required, (4) oxide formation needs to be slow or nonexistent so as to avoid the …

Encapsulated Energy-Transfer Cassettes With Extremely Well Resolved Fluorescent Outputs, Yuichiro Ueno, Jiney Jose, Aurore Loudet, Cesar Perez-Bolivar, Pavel Anzenbacher Jr., Kevin Burgess

Chemistry Faculty Publications

This paper concerns the development of water-compatible fluorescent imaging probes with tunable photonic properties that can be excited at a single wavelength. Bichromophoric cassettes 1a-1c consisting of a BODIPY donor and a cyanine acceptor were prepared using a simple synthetic route, and their photophysical properties were investigated. Upon excitation of the BODIPY moiety at 488 nm the excitation energy is transferred through an acetylene bridge to the cyanine dye acceptor, which emits light at approximately 600, 700, and 800 nm, i.e., with remarkable dispersions. This effect is facilitated by efficient energy transfer that gives a "quasi-Stokes" shift between 86 and …

Tuning The Thermal Relaxation Of Transition-Metal Ferrite Nanoparticles Through Their Intrinsic Magnetocrystalline Anisotropy, Jose M. Vargas, Abhishek Srivastava, Amin Yourdkhani, Luis Zaldivar, Gabriel Caruntu, Leonard Spinu

Chemistry Faculty Publications

Monodispersed ferrite nanoparticles of Fe3O4, MnFe2O4, and CoFe2O4 (near to 10 nm), were synthesized by organometallic synthesis, showing the same homogeneous chemical, morphological, and crystalline characteristics. The study and correlation of the thermal relaxation processes were analyzed through static and dynamic measurements. Due to the intrinsic chemical characteristics and magnetocrystalline anisotropy of the ferrite nanoparticles, the energy barrier can be tuned to a range between 1100 K EB 7300 K, showing an alternative approach for tuning the magnetic dynamic properties, in contrast to the well-known mechanism through particle-size-effects. Specific loss power efficiencies were evaluated for the three ferrite samples. Comparing …

Highly Ordered Transition Metal Ferrite Nanotube Arrays Synthesized By Template-Assisted Liquid Phase Deposition, Amin Yourdkhani, Gabriel Caruntu

Chemistry Faculty Publications

Highly ordered spinel ferriteMxFe3_xO4 (M ¼ Ni, Co, Zn) nanotube arrays were synthesized in anodic aluminium oxide (AAO) templates with a pore size of 200 nm by combining a liquid phase deposition (LPD) method with a template-assisted route. The morphology of the transition metal ferrite nanotubes was characterized by electron microscopy (FE-SEM; TEM, SAED and HRTEM) and atomic force microscopy (AFM), whereas their chemical composition was determined by inductive coupling plasma (ICP). The phase purity was studied by X-ray diffraction (XRD) and the magnetic properties of the nanotubes were measured by SQUID measurements. Unlike the deposition of thin film structures, …

Novel Glycerol-Crosslinked Poly(Acrylic Acid) Hydrogel For Encapsulation And Release Of Benzocaine, Angela Lisandra S. Lee, Gayzen A. Ordoñez, Soma Chakraborty

Chemistry Faculty Publications

Drug delivery by a controlled-release mechanism offers several advantages over traditional delivery systems such as improved therapeutic activity, reduced number of drug administrations, as well as minimizing the risk of over-dose or under-dose. In this study, attempt has been made to develop a novel controlled release device from glycerol crosslinked poly(acrylic acid) hydrogels. Glycerol crosslinked poly(acrylic acid) was fabricated by polymerizing acrylic acid and crosslinking the polymer with glycerol in the same reaction pot in the presence of benzoyl peroxide and Novozym 435. The fabricated hydrogel swelled more than 100% in neutral, acidic and basic buffer solutions. Swelling was pH …

Stabilizing Carbon-Lithium Stars, Nancy Perez-Peralta, Maryel Contreras, William Tiznado, John Stewart, Kelling J. Donald, Gabriel Merino

Chemistry Faculty Publications

We have explored in silico the potential energy surfaces of the C₅Li_n^n-6 (n = 5, 6, and 7) clusters using the Gradient Embedded Genetic Algorithm (GEGA) and other computational strategies. The most stable forms of C₅Li_5-^- and C₅Li₆ are two carbon chains linked by two lithium atoms in a persistent seven membered ring capped by two Li atoms. The other Li atoms are arrayed on the edge of the seven membered ring. In contrast, the global minimum structure for C₅Li₇⁺ is a bicapped star …

Methionine-35 Of Aβ(1-42): Importance For Oxidative Stress In Alzheimer Disease, D. Allan Butterfield, Rukhsana Sultana

Chemistry Faculty Publications

Alzheimer disease (AD) is an age-related progressive neurodegenerative disorder. This devastating disease is characterized by the presence of senile plaques (SP), neurofibrillary tangles (NFTs), and loss of synapses. Amyloid beta-peptide 1–42 (Aβ(1–42)) is the main component of SP and is pivotal to AD pathogenesis. Brain of subjects with AD and arguably its earliest manifestation, mild cognitive impairment (MCI), demonstrate increased levels of oxidative stress markers. Our laboratory combined these two aspects of AD and MCI and proposed the Aβ(1–42)-associated free radical oxidative stress hypothesis to explain oxidative stress under which the MCI and AD brain exist …

Synthesis, Assembly, And Characterization Of Monolayer-Protected Gold Nanoparticle Films For Protein Monolayer Electrochemistry,, Tran T. Doan, Michael H. Freeman, Adrienne R. Schmidt, Natalie T. Nguyen, Michael C. Leopold

Chemistry Faculty Publications

Colloidal gold nanoparticles protected with alkanethiolate ligands called monolayer protected gold clusters (MPCs) are synthesized and subsequently incorporated into film assemblies that serve as adsorption platforms for protein monolayer electrochemistry (PME). PME is utilized as the model system for studying electrochemical properties of redox proteins by confining them to an adsorption platform at a modified electrode, which also serves as a redox partner for electron transfer (ET) reactions. Studies have shown that gold nanoparticle film assemblies of this nature provide for a more homogeneous protein adsorption environment and promote ET without distance dependence compared to the more traditional systems modified …

Charge Saturation And Neutral Substitutions In Halomethanes And Their Group 14 Analogues, Bernard K. Wittmaack, Chad Crigger, Matthew Guarino, Kelling J. Donald

Chemistry Faculty Publications

A computational analysis of the charge distribution in halomethanes and their heavy analogues (MH_4-nX_n: M= C, Si, Ge, Sn, Pb; X = F, Cl, Br, I) as a function of _n uncovers a previously unidentified saturation limit for fluorides when M ≠ C. We examine the electron densities obtained at the CCSD, MP2(full), B3PW91, and HF levels of theory for 80 molecules for four different basis sets. A previously observed substituent independent charge at F in fluoromethanes is shown to be a move toward saturation that is restricted by the low polarizability of C. This limitation …