Chemistry Commons^™

Determination Of Structural Factors Contributing To Protection Of Zinc Fingers In Estrogen Receptor Α Through Molecular Dynamic Simulations, Patricia B. Lutz, Wesley R. Coombs, Craig A. Bayse

Chemistry & Biochemistry Faculty Publications

The ERα transcription factor that induces tumor growth is a potential target for breast cancer treatment. Each monomer of the ERα DNA-binding domain (ERαDBD) homodimer has two conserved (Cys)₄-type zinc fingers, ZF1 (N-terminal) and ZF2 (C-terminal). Electrophilic agents release Zn²⁺ by oxidizing the coordinating Cys of the more labile ZF2 to inhibit dimerization and DNA binding. Microsecond-length molecular dynamics (MD) simulations show that greater flexibility of ZF2 in the ERαDBD monomer leaves its Cys more solvent accessible and less shielded from electrophilic attack by sulfur-centered hydrogen bonds than ZF1 which is buried in the protein. In the …

Phytochemical Analysis, Antioxidant, And Antibacterial Properties Of Partition Fractions Of Adansonia Digitata And Annona Muricata Extracts Using Chloroform, Ethyl Acetate, Ethanol, And Aqueous Solvent Systems, Fagbohun Oyenike Bushirat, Hassan Abdusalam Adewuyi, Sakariyau Adio Waheed, Maryam Nana Musa, Timothy God-Giveth Olusegun, Ayomide Babatunde Ishola, Agumage Idoko, Adeola Victor Kolawole, Adesanmi Adefunmilayo Oluwatuyi, Sarah Ngozi Agwasim

Chemistry & Biochemistry Faculty Publications

Adansonia digitata and Annona muricata are traditionally used medicinal plants with reported pharmacological properties. In this study, we aimed to elucidate the phytochemical composition, antioxidant activity, and antibacterial properties of partition fractions of Adansonia digitata and Annona muricata extracts obtained using chloroform, ethyl acetate, ethanol, and aqueous solvent systems. The plant extracts were successively partitioned using chloroform, ethyl acetate, ethanol, and aqueous solvent systems. Phytochemical analysis was performed using standard methods. Antioxidant activity was evaluated using FRAP and DPPH assays. Antibacterial activity was assessed using agar well diffusion and MIC determination. Phytochemical analysis revealed the presence of alkaloids (10.2-15.6%), flavonoids …

The Importance Of Solution Studies For The Structural Characterization Of The Enterovirus 5' Cloverleaf, Morgan G. Daniels, Meagan E. Werner, Xiaobing Zuo, Steven M. Pascal

Chemistry & Biochemistry Faculty Publications

Enteroviruses initiate genomic replication via a highly conserved mechanism that is controlled by an RNA platform, also known as the 5' cloverleaf (5'CL). Here, we present a biophysical analysis of the 5'CL conformation of three enterovirus serotypes under various ionic conditions, utilizing CD spectroscopy, size-exclusion chromatography, and small-angle X-ray scattering. In general, a tendency toward a smaller monomeric hydrodynamic radius in the presence of salts was observed, but the exact structural signature of each 5'CL varied depending upon the serotype. Rhinovirus B14 (RVB14) exhibited at least two monomeric conformations and a low propensity for dimerization, while poliovirus 1 (PV1) showed …

Unraveling Visible Spectra Of S-Type Stars: The F3Δ–A3Δ (Α System) And E3Π–A3Δ (Β System) Band Systems Of Zro, Manish Bhusal, Peter Bernath, Jacques Liévin

Chemistry & Biochemistry Faculty Publications

ZrO has many low-lying states, and its spectra are essential for the characterization of S-type stars. A high-resolution emission spectrum recorded with a Fourier transform spectrometer at the National Solar Observatory is used for the analysis. The 0–0 and 1–0 bands of the f³Δ-a³Δ system (α system) and the 0–0 band of the e³Π-a³Δ system (β system) have been rotationally analyzed using the modern spectral fitting program PGOPHER. New ab initio calculations of transition dipole moments have been performed to determine the band strengths. These band strengths are used to produce line lists that are suitable for the …

M Star Opacities: The B³Π–X³Δ Band System Of Tio, Peter F. Bernath, Manish Bhusal, Mirek R. Schmidt

Chemistry & Biochemistry Faculty Publications

The spectra of titanium monoxide (TiO) are used to classify M stars. TiO experimental cross sections based on a high-resolution emission spectrum recorded with a Fourier transform spectrometer at the National Solar Observatory are used for the analysis of the TiO B³Π–X³Δ transition (𝛾' system). The 3–2 and 4–3 vibrational bands are analyzed for the first time, and the analysis of the 2–1 band is revised. The transition dipole moment function from an ab initio calculation is used to calculate the band strengths. These band strengths are used to produce a B³Π–X³Δ line list for the vibrational levels v' ⩽ …

A Potentially Fruitful Path Toward A Cleaner And Safer Environment: Mxenes Uses In Environmental Remediation, Ali Mohammad Amani, Milad Abbasi, Atena Najdian, Farzaneh Mohamadpour, Seyed Reza Kasaee, Hesam Kamyab, Shreeshivadasan Chelliapan, Hanieh Ardeshiri, Lobat Tayebi, Ehsan Vafa, Sarah Mosleh-Shirazi, Alireza Jahanbin, Saravanan Rajendran, Daniel Simancas-Racines

Electrical & Computer Engineering Faculty Publications

The rapid industrialization of the world has resulted in severe environmental pollution, necessitating the development of new materials such as pollution remediation. Two-dimensional (2D) MXenes have emerged as a promising family of materials due to their unique physicochemical properties, making them ideal for environmental remediation. The article sheds light on the new opportunities of MXenes in the removal of organic and inorganic contaminants, including organic dyes, pharmaceuticals, heavy metals, radionuclides, and gas pollutants. MXenes also show excellent performance in photocatalytic degradation, adsorption, and microbial inactivation with environmental safety. Moreover, their application in recovering valuable elements from waste streams is also …

Use Of Cobalt(Iii) And Copper(Ii) Complexes With Thiosemicarbazone Ligands And Berberine Chloride As Anti-Cancer Agents Against Triple Negative Breast Cancer, Duaa Rashad Alajroush

Chemistry & Biochemistry Theses & Dissertations

It is a worrying fact that chemotherapeutic options for treating triple negative breast cancer are limited in nature, including the use of inorganic pharmaceuticals such as cisplatin and its analogues. It has been reported that cisplatin has undesirable side effects when used as a chemotherapeutic drug. As such, there is a need to use non-platinum-containing complexes as chemotherapeutic agents. Based on that issue, it has been reported by our research group and others that cobalt- and copper-containing complexes have shown great potential in anti-cancer properties when compared to cisplatin. In this research project, the cytotoxic effects of the following complexes: …

Synthesis And Characterization Of Cobalt-Based Complexes And Metal-Organic Frameworks For Hydrogen Evolution Catalysis Under Acidic Conditions, Elizabeth A. Tonsel-White

Chemistry & Biochemistry Theses & Dissertations

The synthesis of two cobalt(II) complexes: the novel complex [Co(phen)₃]₂[Co(pytc)₂]•16.25H₂O 1 and the previously reported [Co(bpy)₃](OH)₂•7H₂O 2, along with a cobalt(II/III)-containing MOF, Co-PPF2, previously reported as well, was achieved. These complexes were characterized by elemental analysis, X-ray crystallography, microscopy, conductivity measurements, TGA, SEM, CV , and UV-visible , and FTIR spectroscopies. From the CV scan rates, diffusion coefficients for complexes 1 and 2 were determined to be 1.0 × 10⁻⁶ cm² s⁻¹ and 4.8 × 10⁻⁷ cm² s⁻¹. Electrocatalytic studies with complexes 1 and 2 revealed insights into the mechanistic aspects of …

Study Of Atypical Alarmone Synthesis In Clostridioides Difficile, Declan Nathaniel Butler

Chemistry & Biochemistry Theses & Dissertations

Clostridioides difficile is a Gram-positive anaerobic bacterium that causes infections in humans that costs healthcare systems billions per year. C. difficile infection has high rates of recurrence due to multiple antibiotic resistance. When bacteria are in stressful environments, they produce hyperphosphorylated guanosine ribonucleotide signaling molecules called alarmones. The accumulation of alarmones activates the stringent response (SR), in which bacterial cells induce transcription of stress survival genes to delay growth and replication. The C. difficile SR is regulated by enzymatic activity of a bifunctional synthetase/hydrolase, RelA/SpoT homolog (RSH), and a monofunctional small alarmone synthetase (RelQ). Additionally, the SR is potentially regulated …

Attendance At Virginia Academy Of Science Meetings: A Report Of The Panel Discussion Held By The Chemistry Section Of The Virginia Academy Of Science, Tom Devore

Virginia Journal of Science

Since the attendance in the Chemistry Section at the Virginia Academy of Science (VAS) spring meetings has not returned to the numbers attending prior to the cancellation of the 2020 meeting due to the Covid pandemic, a roundtable discussion was held as part of the 2023 VAS Annual Meeting at the College of William and Mary on May 25, 2023 to discuss possible ways to increase attendance at future meetings. This is a report of the topics discussed and the suggestions made.

Virginia Academy Of Science At 100: A Presentation Given To The Chemistry Section Of The Virginia Academy Of Science, Tom Devore

Virginia Journal of Science

While I have not been an active member of the Virginia Academy of Sciences (VAS) for all of its 100 years of existence, I have seen many changes in VAS during the more than 30 years that I have been an active member. This paper, delivered at the VAS Annual Meeting at the College of William and Mary on May 25, 2023, recalls some of the outstanding scientists in Virginia that I have had the privilege of knowing and who have led and lived out the goals of VAS. They inspired me to try to live up to the high …

Exploring Cation Exchange: Unveiling Its Significance In Biochar And Bioenergetics Applications, Gyanendra Kharel

Chemistry & Biochemistry Theses & Dissertations

Cation exchange, a cornerstone of soil chemistry and nutrient cycling, is a fundamental chemical process that occurs in soils, sediments, membranes, and other solid materials. It involves the interchange of positively charged ions, or cations, between a solid matrix and a surrounding solution. This process is crucial in various natural and engineered systems, leading to a range of applications across different fields.

This dissertation presents an extensive investigation into the applications of cation exchange in the fields of biochar and bioenergetics, encompassing three distinct aims. The first aim concentrates on the surface oxygenation of biochar through ozonization, aiming to achieve …

Broadband Dielectric Spectroscopic Detection Of Volatile Organic Compounds With Zinc Oxide And Metal-Organic Frameworks As Solid-State Sensor Materials, Papa Kojo Amoah

Electrical & Computer Engineering Theses & Dissertations

The industrial revolution drove technological progress but also increased the release of harmful pollutants, posing significant risks to human health and the environment. Volatile organic compounds (VOCs), which have various anthropogenic and natural sources, are particularly concerning due to their impact on public health, especially in urban areas. Addressing these adverse effects requires comprehensive strategies for mitigation as traditional gas sensing techniques have limitations and there is a need for innovative approaches to VOC detection.

VOCs encompass a diverse group of chemicals with high volatility, emitted from various human activities and natural sources. These compounds play a crucial role in …

Spectroscopy Of Atmospheres, Randika Dodangodage

Physics Theses & Dissertations

Spectroscopic methods are used to study planetary and stellar atmospheres. The information obtained from spectroscopic studies provides insight into atmospheric compositions and dynamics, which can be used to model and characterize atmospheres and climates. Laboratory-recorded absorption cross-sections are needed to interpret the recorded spectra of planets and stars. High resolution ethane, neopentane, propene, and n-butane spectra have been recorded, and absorption cross-sections have been provided for different temperatures and total pressures with different broadening gases, including hydrogen, helium, and nitrogen. The Atmospheric Chemistry Experiment (ACE) satellite orbits Earth and records spectra through solar occultation limb observations. HOCl is a chlorine …

Reiq-Mediated Alarmone Signalling Regulates Growth, Stress-Induced Biofilm Formation And Spore Accumulation In Clostridioides Difficile, Areej Malik, Adenrele Oludiran, Asia Poudel, Orlando Berumen Alvarez, Charles Woodward, Erin B. Purcell

Chemistry & Biochemistry Faculty Publications

The bacterial stringent response (SR) is a conserved transcriptional reprogramming pathway mediated by the nucleotide signalling alarmones, (pp)pGpp. The SR has been implicated in antibiotic survival in Clostridioides difficile, a biofilm- and spore-forming pathogen that causes resilient, highly recurrent C. difficile infections. The role of the SR in other processes and the effectors by which it regulates C. difficile physiology are unknown. C. difficile RelQ is a clostridial alarmone synthetase. Deletion of relQ dysregulates C. difficile growth in unstressed conditions, affects susceptibility to antibiotic and oxidative stressors and drastically reduces biofilm formation. While wild-type C. difficile displays increased biofilm …

Multiple Variables Influence The Finely Calibrated Antioxidant Defenses Of Clostridioides Difficile, Erin B. Purcell

Chemistry & Biochemistry Faculty Publications

The obligate anaerobe Clostridioides difficile encodes multiple reductases to detoxify molecular oxygen and reactive oxygen species. Caulat and colleagues have characterized the activity and regulation of four such reductases (L. C. Caulat, A. Lotoux, M. C. Martins, N. Kint, et al., mBio 15:e01591-24, 2024, https://doi.org/10.1128/mbio.01591-24). Each proved critical for clostridial survival in a different range of oxygen concentrations; together, they ameliorate a broad range of oxidative stress levels. Moreover, two previously uncharacterized regulators were found to control reductase gene expression in response to oxidative stress. The genetic repressor Rex and the reductase FdpF are both sensitive to the NAP …

The A²Π-X²Σ⁺ Band System Of Sco For M-Type Star Spectral Analysis, Léo Lavy, Adam Pastorek, Peter F. Bernath

Chemistry & Biochemistry Faculty Publications

M-type stars are the most abundant stars in our Galaxy. Their visible spectra are characterized by strong TiO and VO absorption bands with occasional ScO bands near 6000–6100 Å. This region corresponds to the A²Π–X²Σ⁺ band system and can be used to measure the abundance of ScO. In this work, a new Doppler-limited resolution spectrum of ScO obtained in a hollow-cathode experiment is presented. The A²Π–X²Σ⁺ electronic transition is analyzed with special care dedicated to fitting the A′²Δ(v+2) ∼ A²Π(v) perturbation. Spectroscopic constants of the A²Π(v) states are reported for v ≤ 9, and a partial fit of …

Enhancement Of Antitumor Effects Of Berberine Chloride With A Copper(Ii) Complex Against Human Triple Negative Breast Cancer: In Vitro Studies, Duaa R. Alajroush, Brittney F. Anderson, Janae A. Bruce, Christian I. Lartey, Dazonte A. Mathurin, Sean T. Washington, Tanaya S. Washington, Sidy Diawara, Sakariyau A. Waheed, Kaylin L. Thomas, Stephen J. Beebe, Alvin A. Holder

Chemistry & Biochemistry Faculty Publications

In this study, the copper(II) complex [Cu(chromoneTSC)Cl₂]•0.5H₂O•0.0625C₂H₅OH (where chromoneTSC = (E)-N-Ethyl-2-((4-oxo-4H-chromen-3-yl)methylene)-hydrazinecarbothioamide) was synthesized and characterized; then used to carry out in vitro studies in combination with berberine chloride (BBC). The ligand and complex were characterized by elemental analysis, FTIR and NMR (¹H and ¹³C) spectroscopy, and conductivity measurements. The cytotoxic effect was analyzed by using the CCK-8 viability assay in cancer MDA-MB-231 VIM RFP and non-cancer MCF-10A cell lines. The IC₅₀ values for the complex and BBC were 21.2 ± 1.6 and 48.3 ± 2.4 μM, respectively at 24 h incubation, while the IC₅₀ value of the combination treatment …

A New Approach For Discriminating Spatially Acquired Sers Spectra Using Antiretroviral Drug Emtricitabine As A Test Sample, Jana Hrncirova, Marguerite R. Butler, Meredith R. Clark, Gustavo F. Doncel, John B. Cooper

Chemistry & Biochemistry Faculty Publications

In this study, an antiretroviral drug emtricitabine (also known as FTC or Emtriva) was detected and quantified down to 40 ng/ml by using surface-enhanced Raman spectroscopy (SERS). Its aqueous standards were tested with two types of silver nanoparticles (colloidal and dendritic) using a specially developed aluminum well plate. The SERS spectra were acquired using a Raman scanning device with 30-mu m spatial resolution. The spectral data were analyzed using a new approach for the discrimination of the spatially acquired spectra based on the Quality index (Qi). After the Qi is calculated, the spectral data are sorted based on the Qi. …

Type-B Energetic Processes: Introduction And Invitation To Special Issue Of Energies, James Weifu Lee, Daniel P. Sheehan

Chemistry & Biochemistry Faculty Publications

[First paragraph] Currently, there is substantial scientific evidence for the existence of Type-B energetic processes on Earth, such as the naturally occurring transmembrane-electrostatically localized protons (TELP) thermotrophic properties in life [1]. A number of groundbreaking human-made Type-B energetic processes, including (but not limited to) “asymmetric function-gated isothermal electricity production” [2], “epicatalysis generating a temperature difference between catalysis-asymmetric filaments” [3], “artificially made asymmetric membrane concentration cell” [4,5], “Fu’s experiment on heat–electric conversion using surface electron emission under a static magnetic field” [6], and the “dynamic processes in superconductors indicating Type-B energetic process” [7,8,9] have been invented and/or experimentally demonstrated. The innovative …

Trends In Atmospheric Composition Between 2004-2023 Using Version 5 Ace-Fts Data, Matthew Schmidt, Peter Bernath, Chris Boone, Michael Lecours, Johnathan Steffen

Chemistry & Biochemistry Faculty Publications

The Atmospheric Chemistry Experiment (ACE) is a satellite mission that has been in orbit since 2003. The primary instrument on ACE is a Fourier transform spectrometer (FTS) that records infrared atmospheric transmittance spectra in the limb geometry using the Sun as a light source. Version 5 of ACE-FTS data processing contains improved volume mixing ratio (VMR) profiles for 46 molecules and 24 isotopologues, including HFC-32 (CH₂F₂) and HOCl as new routine data products. VMR trends for each of the 46 molecules are reported for regions of atmospheric interest. Specifically, the longevity of the ACE mission has …

Stabilization Of Pfas-Contaminated Soil With Sewage Sludge- And Wood-Based Biochar Sorbents, Erlend Sørmo, Clara Benedikte Mader Lade, Julie Zhang, Alexandros G. Asimakopoulos, Geir Wold Åsli, Michel Hubert, Aleksandar I. Goranov, Hans Peter H. Arp, Gerard Cornelissen

Chemistry & Biochemistry Faculty Publications

Sustainable and effective remediation technologies for the treatment of soil contaminated with per- and polyfluoroalkyl substances (PFAS) are greatly needed. This study investigated the effects of waste-based biochars on the leaching of PFAS from a sandy soil with a low total organic carbon content (TOC) of 0.57 ± 0.04% impacted by PFAS from aqueous film forming foam (AFFF) dispersed at a former fire-fighting facility. Six different biochars (pyrolyzed at 700–900°C) were tested, made from clean wood chips (CWC), waste timber (WT), activated waste timber (aWT), two digested sewage sludges (DSS-1 and DSS-2) and de-watered raw sewage sludge (DWSS). Up-flow column …

Green Oxidation Of Aromatic Hydrazide Derivatives Using An Oxoammonium Salt, Nidheesh Phadnis, Jessica A. Molen, Shannon M. Stephens, Shayne M. Weierbach, Kyle M. Lambert, John A. Milligan

Chemistry & Biochemistry Faculty Publications

Aromatic diazenes are often prepared by oxidation of the corresponding hydrazides using stoichiometric quantities of nonrecyclable oxidants. We developed a convenient alternative protocol for the oxidation of aromatic hydrazides using Bobbitt's salt (1), a metal-free, recyclable, and commercially available oxoammonium reagent. A variety of aryl hydrazides were oxidized within 75 min at room temperature using the developed protocol. Computational insight suggests that this oxidation occurs by a polar hydride transfer mechanism.

Unraveling Sources Of Cyanate In The Marine Environment: Insights From Cyanate Distributions And Production During The Photochemical Degradation Of Dissolved Organic Matter, Rui Wang, Jihua Liu, Yongle Xu, Li Liu, Kenneth Mopper

Chemistry & Biochemistry Faculty Publications

Cyanate is a nitrogen and energy source for diverse marine microorganisms, playing important roles in the nitrogen cycle. Despite the extensive research on cyanate utilization, the sources of this nitrogen compound remain largely enigmatic. To unravel the sources of cyanate, distributions and production of cyanate during photochemical degradation of natural dissolved organic matter (DOM) were investigated across various environments, including freshwater, estuarine, coastal areas in Florida, and the continental and slope regions of the North American mid-Atlantic Ocean (NATL). Cyanate production was also examined during the photochemical degradation of exudates from a typical strain of Synechococcus, an important phytoplankton …

Evidence Of Direct Interaction Between Cisplatin And The Caspase-Cleaved Prostate Apoptosis Response-4 Tumor Suppressor, Krishna K. Raut, Samjhana Pandey, Gyanendra Kharel, Steven M. Pascal

Chemistry & Biochemistry Faculty Publications

Prostate apoptosis response-4 (Par-4) tumor suppressor protein has gained attention as a potential therapeutic target owing to its unique ability to selectively induce apoptosis in cancer cells, sensitize them to chemotherapy and radiotherapy, and mitigate drug resistance. It has recently been reported that Par-4 interacts synergistically with cisplatin, a widely used anticancer drug. However, the mechanistic details underlying this relationship remain elusive. In this investigation, we employed an array of biophysical techniques, including circular dichroism spectroscopy, dynamic light scattering, and UV–vis absorption spectroscopy, to characterize the interaction between the active caspase-cleaved Par-4 (cl-Par-4) fragment and cisplatin. Additionally, elemental analysis was …

Reducing The Uncertainty In Estimating Soil Microbial-Derived Carbon Storage, Han Hu, Chao Qian, Ke Xue, Rainer Georg Jörgensen, Marco Keiluweit, Chao Liang, Xuefeng Zhu, Ji Chen, Yishen Sun, Haowei Ni, Jixian Ding, Weigen Huang, Jingdong Mao, Rong-Xi Tan, Jizhong Zhou, Thomas W. Crowther, Zhi-Hua Zhou, Jiabao Zhang, Yuting Liang

Chemistry & Biochemistry Faculty Publications

Soil organic carbon (SOC) is the largest carbon pool in terrestrial ecosystems and plays a crucial role in mitigating climate change and enhancing soil productivity. Microbial-derived carbon (MDC) is the main component of the persistent SOC pool. However, current formulas used to estimate the proportional contribution of MDC are plagued by uncertainties due to limited sample sizes and the neglect of bacterial group composition effects. Here, we compiled the comprehensive global dataset and employed machine learning approaches to refine our quantitative understanding of MDC contributions to total carbon storage. Our efforts resulted in a reduction in the relative standard errors …

Potentially Massive And Global Non-Pyrogenic Production Of Condensed "Black" Carbon Through Biomass Oxidation, Aleksandar I. Goranov, Hongmei Chen, Jianshu Duan, Satish C. B. Myneni, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

With the increased occurrences of wildfires worldwide, there has been an increase in scientific interest surrounding the chemistry of fire-derived "black" carbon (BC). Traditionally, wildfire research has assumed that condensed aromatic carbon (ConAC) is exclusively produced via combustion, and thus, ConAC is equated to BC. However, the lack of correlations between ConAC in soils or rivers and wildfire history suggests that ConAC may be produced non-pyrogenically. Here, we show quantitative evidence that this occurs during the oxidation of biomass with environmentally ubiquitous hydroxyl radicals. Pine wood boards exposed to iron nails and natural weather conditions for 12 years yielded a …

Synthetic Approaches Of Carbohydrate Based Self-Assembling Systems, Guijun Wang, Anji Chen, Pramod Aryal, Jonathan Bietsch

Chemistry & Biochemistry Faculty Publications

Carbohydrate-based self-assembling systems are essential for the formation of advanced biocompatible materials via a bottom-up approach. The self-assembling of sugar-based small molecules has applications encompassing many research fields and has been studied extensively. In this focused review, we will discuss the synthetic approaches for carbohydrate-based self-assembling (SA) systems, the mechanisms of the assembly, as well as the main properties and applications. This review will mainly cover recent publications in the last four years from January 2020 to December 2023. We will essentially focus on small molecule self-assembly, excluding polymer-based systems, which include various derivatives of monosaccharides, disaccharides, and oligosaccharides. Glycolipids, …

Assessing The Spatiotemporal Variability Of Dissolved Organic Matter Fluorescence Composition In The Lake George, Ny Watershed, Aleksandar I. Goranov, Mark W. Swinton, David A. Winkler, Jeremy L. Farrell, Sandra A. Nierzwicki-Bauer, Sasha Wagner

Chemistry & Biochemistry Faculty Publications

Lake George (LG) is a temperate, oligotrophic, medium-sized lake (114 km²) located in northeastern New York State (U.S.). Lakes are highly understudied environments where extensive dissolved organic matter (DOM) processing occurs. With this study we establish the foundation for researching the organic biogeochemistry of the LG watershed, in particular, the numerous tributaries flowing into the lake. Collected were 213 samples from 64 tributaries and 12 lake locations. Some of the tributaries had unique wastewater, agricultural, or wetland influences. We employed fluorescence spectroscopy, a common biogeochemical technique, to characterize the fluorescent DOM (FDOM) component. We developed a parallel factor …

Photoluminescence Switching In Quantum Dots Connected With Carboxylic Acid And Thiocarboxylic Acid End-Group Diarylethene Molecules, Ephraiem S. Sarabamoun, Pramod Aryal, Jonathan M. Bietsch, Maurice Curran, Sugandha Verma, Grayson Johnson, Lucy U. Yoon, Amelia G. Reid, Esther H. R. Tsai, Charles W. Machan, Christopher Paolucci, Guijun Wang, Joshua J. Choi

Chemistry & Biochemistry Faculty Publications

We contrast the switching of photoluminescence (PL) of PbS quantum dots (QDs) cross-linked with photochromic diarylethene molecules with different end groups, 4,4′-(1-cyclopentene-1,2-diyl)bis[5-methyl-2-thiophenecarboxylic acid] (1C) and 4,4′-(1-cyclopentene-1,2-diyl)bis[5-methyl-2-thiophenethiocarboxylic acid] (2T). Our results show that the QDs cross-linked with the carboxylic acid end group molecules (1C) exhibit a greater amount of switching in photoluminescence intensity compared to QDs cross-linked with the thiocarboxylic acid end group (2T). We also demonstrate that regardless of the molecule used, greater switching amounts are observed for smaller quantum dots. Varying these parameters allows for the fabrication of photoswitches with tunable PL change. We relate these observations to the …