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Main Group Chemistry:
12:00pm - 02:00pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual Room
Todd Hudnall, Organizer
Division: [INOR] Division of Inorganic Chemistry
Session Type: Poster - Virtual
Division/Committee: [INOR] Division of Inorganic Chemistry
Thursday
3646596 - Withdrawn
12:00pm - 02:00pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual Room
Session Type: Poster - Virtual

Thursday
3654512 - Withdrawn
12:00pm - 02:00pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual Room
Session Type: Poster - Virtual

Thursday
3658157 - Withdrawn
12:00pm - 02:00pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual Room
Division: [INOR] Division of Inorganic Chemistry
Session Type: Poster - Virtual

Thursday
3659952 - Reactivity of disilene as silylene towards Lewis acids
12:00pm - 02:00pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual Room
Nilanjana Sen, Presenter
Division: [INOR] Division of Inorganic Chemistry
Session Type: Poster - Virtual
Synthesis of highly short lived reactive intermediate in laboratory has remained as an intriguing topic for synthetic chemists since a long time. Gradually a keen interest to synthesis the highly reactive higher analogues of carbene that is silylene, germylenes and stannylenes developed among the scientists.1 Much before this existence of double bonds between the higher analogues of group 14 elements was perceived by Lappert’s report of Sn=Sn in 19732 followed by the breakthrough report of disilene synthesis in 1981 by West and Fink.3 Trans bent geometry and the presence of equilibrium with their corresponding silylene along with the less HOMO-LUMO gap facilitates more reactivity in disilene than carbenes.4
Our group has also focused to synthesize disilene5 and also investigated the pattern of reactivity with different p block halides and subsequently explored the behavior of disilene as its corresponding silylene. The paucity of disilene Lewis acid complexes actually triggered our minds to study the reaction of disilene with different p block Lewis acids as well as halide containing compounds. In doing so we have performed some reactivities with different Lewis acids like BCl3, AlCl3, AlBr3 and low valent group 14 halide containing compounds which afforded different types of products in each cases.

Thursday
3660022 - Bis(Silatellurone) with C-H-Te interaction
12:00pm - 02:00pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual Room
MOUSHAKHI GHOSH, Presenter
Division: [INOR] Division of Inorganic Chemistry
Session Type: Poster - Virtual
Herein, we attempted to synthesize Silicon-Carbon-Silicon pincer based Bissila-chalcogenones (O, S, Se, Te), which shows intramolecular C-H-Ch (Ch= S, Se, Te) interaction which are being validated by X-Ray diffraction, temperature-dependent 1H-NMR in combination with natural bonding orbital (NBO) analysis.[1] Over the years, C-H-O/S interactions have been found in protein and peptide and proven to be crucial for their stability but C-H-Te interactions are less observed in this context. Our work deals with an in-depth analysis of the bonding pattern and the stability of non-covalent interactions. This gives idea of the chemical environment of proton involved in the interaction, which gives the basis of fundamental understanding of C-H-Ch interaction and the role of silylene for lending polarity to chalcogens.
Lanthanide and Actinide Chemistry:
12:00pm - 02:00pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual Room
Division: [INOR] Division of Inorganic Chemistry
Session Type: Poster - Virtual
Division/Committee: [INOR] Division of Inorganic Chemistry
Thursday
3641396 - Magnetic resonance thermometry using a GdIII-based contrast agent
12:00pm - 02:00pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual Room
Division: [INOR] Division of Inorganic Chemistry
Session Type: Poster - Virtual
Magnetic resonance imaging (MRI) is a noninvasive imaging technique that is widely used to diagnose diseases and guide therapies. MRI is often improved with respect to sensitivity through the use of chemicals known as contrast agents. The combination of MRI with temperature-responsive contrast agents has the potential to increase the ability to accurately map real-time temperatures. Lanthanide-based contrast agents for MRI have been encapsulated in macromolecular hydrogel systems or thermosensitive liposomes to increase contrast upon increasing temperature. However, there is a lack of small-molecule MRI thermometers that transition from dark to bright with increasing temperature. We drew inspiration from a previously reported redox-responsive fluorinated EuII-containing complex that exhibited a temperature-dependent increase in relaxivity. We hypothesized that replacing EuII with GdIII would isolate temperature control from redox activity if the coordination chemistry remained similar. In their solid-state, fluorinated complex possesses a cage-like structure that was formed by the fluorinated tetra-amide arms. However, methylated tetra-amide arms are extending away from the GdIII ion. Relaxivity of the fluorinated complex was remained constant at 1.9 mM–1 s–1 from 293 to 318 K at 9.4 T with an increase in innersphere relaxivity over the same range at both 1.4 and 9.4 T. Further, we observed a steady decrease in the relaxivity, both observed and innersphere, of the methylated complex with increasing temperature. The calculated water-exchange rate of fluorinated complex is an order of magnitude slower than the water-exchange rate of methylated analog over the entire temperature range that we studied. These studies are a critical step toward the design of temperature-sensitive contrast agents.
Thursday
3656834 - Four terbium in orthogonal arrangement with [AsW9O33]9- shows zero field slow magnetic relaxation
12:00pm - 02:00pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual Room
Sandhya Sandhya, Presenter
Division: [INOR] Division of Inorganic Chemistry
Session Type: Poster - Virtual
SMMs are one of the promising fields of research that has attracted enormous attention in the past few decades, because of their unique and intriguing properties and potential applications in molecular spintronics, data storage, and quantum computing. In this regard, nonmagnetic polyoxometalates (POMs) are a good candidate and substitute organic ligands for Ln-SMMs because of some advantageous chemical, structural and electronic features that make them applicable for this aim. Taking these considerations in mind, we are interested to synthesize the POM-ligated lanthanide complex by using a symmetric type of POM. The dilacunary precursor is a versatile POM that can disintegrate to lacunary POM and isomerize in the presence of alkali metal and at different pH values. The lacunary POM tends to bind to Ln with the coordination geometry similar to bis(phthalocyaninato)lanthanide complexes. Here we have reported, Polyoxometalate ligated tetranuclear rare earth metal complexes having molecular formula As4CsxK24-xO168Ln4W36 {x = 5, Ln = Tb(III) (1), x = 6, Ln = Dy(III) (2)} were synthesized and characterised. The building unit [AsW9O33]9-, is linked by four rare-earth ions, which are orthogonal to each other forming a windmill-like structure. Detailed magnetic studies disclose the presence of large easy-axis anisotropy and slow relaxation behavior in the absence of an external magnetic field. Notably, this is the first example of Tb-based POM showing SMM behavior in the absence of an external field.
Thursday
MEDI Coffee Hour
02:00pm - 03:00pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual Room
Division: [MEDI] Division of Medicinal Chemistry
Session Type: Networking Events - Virtual
Division/Committee: [MEDI] Division of Medicinal Chemistry
Biomaterials and Biointerfaces:
03:00pm - 06:45pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 7
Emanuela Andreescu, Organizer, Presider; Charles Collier, Organizer; Simona Hunyadi Murph, Organizer; Wade Zeno, Organizer
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
Division/Committee: [COLL] Division of Colloid & Surface Chemistry

This symposium will cover all topics of interest to biologically relevant research in colloid and surface science focusing on biological interfaces and the interaction of abiotic material surfaces with biological systems. Areas of interest include the theory, principles, design, and synthesis of biomaterials; the use of biomaterials in tissue engineering; characterization of new or existing biomaterials; and the interactions of biomaterials with proteins, membranes, cells, and tissues.

Thursday
Introductory Remarks
03:00pm - 03:05pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 7
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual

Thursday
3644946 - Transparent surface coatings that kill antimicrobial-resistant bacteria and inactivate the COVID-19 virus within minutes
03:05pm - 03:25pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 7
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
Pathogens can be transferred between solid surfaces and humans. An engineering method of inhibiting the spread of disease is to employ surface coatings that inactivate or kill pathogens. Although the primary function of such a coating is antimicrobial, consumer acceptance depends on appearance, and customer discovery suggests that a transparent coating is much preferred over colored coatings. We have developed two coatings that are both antimicrobial and transparent. The coatings use polydopamine (PDA) as the adhesive. The PDA polymerizes from monomers on the surface and forms an adhesive layer around the solid particles that binds them to the solid surface. Our first coating (PDA/Cu2O) was made by simultaneous deposition of a suspension containing both dopamine and Cu2O particles followed by surface polymerization. We used a sparse layer of particles to prepare a coating that is transparent. For our second coating (PDA/Cu), the PDA layer was made first, and then a layer of copper was grown on the PDA via electroless deposition. The copper layer was thin to maintain the transparency of the coating. PDA/Cu2O coating kills Pseudomonas aeruginosa (by 99.94%) and methicillin-resistant Staphylococcus aureus (MRSA; by 96.82%), within 10 minutes, and inactivates 99.88% of COVID-19 virus (SARS-CoV-2) within 1 hr. PDA/Cu coating kills Pseudomonas aeruginosa (by >99.99%) and MRSA (by 99.18%), within 10 minutes, and inactivates 99.98% of SARS-CoV-2, within 1 hr.
Thursday
3648464 - Engineered nanotopography on 3D-printed polymer scaffolds to impart mechanobactericidal property
03:25pm - 03:45pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 7
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
Bone is one of the most widely transplanted tissues of the human body. With increasing lifespan and incidences of lifestyle diseases, aside from trauma and congenital disorders, there is an ever-growing demand for bone tissue engineering. A 3D biodegradable scaffold that serves as a temporary construct is essential to facilitate new tissue growth at the defect site. However, the recurrent implant-associated infection due to bacterial attack at the surgical site puts an enormous clinical and economic burden, especially with rising cases of antimicrobial resistance. Infection at the surgical site arises as bacteria penetrate the defect site during a surgical procedure and colonize the biomaterial surface, which has been a significant problem in orthopedic surgery.
Nanopillars (NPs) present on some insect wings can physically rupture bacteria in a manner independent of the conventional chemical mechanisms. Such bactericidal surfaces in nature offer motivation for the fabrication of biomimetic bactericidal nanostructures on biomedical devices. The existing methods used to make NPs on metallic surfaces cannot be used for biomedical devices made up of biodegradable, low melting point polymers, and this has been a real challenge.
This study aims to develop scalable surface modification processes capable of producing bactericidal nanotopography (NT) on polymer scaffolds. The goal was to physically alter the surface topography of the as-printed 3D polymer scaffold to make it effective against a wide range of bacteria without using chemical agents. The 3D spin coating setup was developed for 3D scaffolds with a flexible fixture to hold the scaffolds. Polymer demixing property of polycaprolactone (PCL)/poly(methyl methacrylate) (PMMA) was used to fabricate NP topography on polylactic acid (PLA) 3D printed scaffolds. The spin coating at high speed generated the NT due to the immiscible nature of polymer in a common solvent and the difference in molecular weight. The fabricated NT on the scaffold surface was tested against E. coli and S. aureus strains. Various ratios of the PCL and PMMA were tried to obtain NT on the modified scaffold. The NT significantly inhibited bacterial growth, as revealed by fluorescence images. This is attributed to the NPs fabricated on the scaffold surface that physically ruptures the bacterial membrane. Hence, the leaching-free, antibacterial, and biocompatible polymer scaffolds can be directly employed in bone tissue regeneration.

Thursday
3649311 - Modularly designed polyacrylate microgels for antibacterial activity against Staphylococcus aureus
03:45pm - 04:05pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 7
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
Rapid evolution of antibiotic resistant bacteria requires consistent development of antimicrobial agents for which resistance mechanisms are not known. Polymeric structures decorated with transition metal complexes pose a promising strategy for this purpose by offering unique mechanisms of action and the potential to evade common resistance strategies. A series of structure-activity relationship studies using polyacrylate microgels with embedded copper(II) complexes in broth microdilution assays with Staphylococcus aureus demonstrated that antimicrobial activity of the material is related to modular design in terms of co-monomer polarity, Cu(II) ion binding strength of polymerizable ligands, and counterion coordination to metal complexes during synthesis. A microgel Cu2LP(EG) (L = VBbsdpo) emerged with optimized minimum inhibitory concentration of 0.39 ± 0.03 μg/mL resulting from synthesis using 60 mol% of crosslinking ethyleneglycol dimethacrylate, 40 mol% butyl acrylate, 0.5 mol% VBbsdpo ligand in the presence of 1 mol% Cu(II) ions and 5 mol% ethylene glycol counterions. Insight into antimicrobial properties reveal stable activity for a shelf life of greater than 18 months. Bactericidal activity toward S. aureus was observed at a concentration of 1.5x the MIC in less than 15 minutes. Additionally, 260 nm release assays indicate mechanism of action involves damage to bacterial membrane beyond repair. Despite having potent antimicrobial activity, there was no cytotoxic effect observed from microgels at their minimum inhibitory concentrations toward human dermal fibroblasts for 20 h exposure.
Thursday
3651049 - Influence of efflux on molecular transport across bacterial membranes
04:05pm - 04:25pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 7
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
Molecular efflux is a process by which a bacterium actively removes unwanted compounds from its interior in order to preserve viability. This mechanism is used by bacteria to stave off active antimicrobial attacks or prevent overindulging on otherwise helpful nutrients. Herein, we quantify the influence of efflux on the molecular uptake kinetics of an exogenous molecule - the bacterial uptake of the hydrophobic ion, malachite green (MG), by a colloidal suspension of P. Aeruginosa. MG is a quaternary ammonium cation and is known to be weakly antibiotic towards Gram-negative strains. Above a critical concentration, MG ions should be recognized by the RND efflux pumps of P. Aeruginosa and removed from the cell. As a test of this hypothesis, we used time-resolved second harmonic light scattering (SHS) to monitor the concentration dependent interactions of MG ions with the membranes of P. Aeruginosa. Indeed, above ca. 10 mM MG, the MG ions were recognized by the efflux pumps and were being removed from the cells.

The effect of a second effluxable compound, hexane at the saturation concentration in water which is expected to reduce the efficacy of the efflux pumps, was also examined. Indeed, when hexane was present, the deduced MG transport rate was observed to increased closer to the non-efflux value.

Importantly, we note that when the effect of efflux on transport is included in the kinetic model for quantitative description of the bacterial membrane transport, we were able to 1) accurately account for the MG concentration dependent changes in the membrane transport rate and 2) deduce the rate of efflux of MG. Finally, application of competitive efflux for deducing the propensity for efflux and determining the efflux rate of the non-SHS active molecule will be presented.

Thursday
3652176 - Mimics of natural organelles and cells by equipping synthetic compartments with stimuli-responsive assemblies and biomolecules
04:25pm - 04:45pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 7
Cornelia Palivan, Presenter
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
In various domains, including medicine, food sciences, ecology sciences, technology there are necessary to design and develop new concepts that combine active compounds with stable, safe carriers or membranes resulting in multifunctional systems. In particular, suitable amphiphilic block copolymers are ideal candidates for generation of 3D supramolecular assemblies, such as compartments, micelles, nanotubes or planar membranes. The polymeric assemblies can be combined with biomolecules by their encapsulation inside the cavity of the compartments, attachment at the surface, insertion inside the planar membranes, etc in order to provide well-defined functions, such as molecular recognition, cooperation, and catalytic activity.
Here, we present distinct spaces for desired reactions or signaling pathways based on combining polymer assemblies with stimuli-respnsive nanoassemblies and biomolecules. The aim is to develop multifunctional systems that play the role of artificial organelles when internalized in cells or serve as simple mimics of cells. Biopores/channel proteins inserted into the polymer membrane selectively control the exchange of substrates and products, resulting in development of stimuli-responsive compartments, which preserve their architecture, while allowing specific in situ reactions. In a complementary approach, stimuli-responsive nanoparticles encapsulated inside giant polymer vesicles serve for recruitment of biopores and thus trigger catalytic reactions inside. This general strategy supports the development of artificial organelles, proved to be functional in vitro and in vivo and of simple processes in artificial cells.

Thursday
Intermission
04:45pm - 05:00pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 7
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual

Thursday
3654365 - Polyelectrolyte-based biomaterials: Influence on protein structural stability
05:00pm - 05:20pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 7
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
Biomaterials and nano-assemblies composed of proteins and charged macromolecules find important applications as pharmaceutical formulations, biocatalysts, drug delivery vehicles, and cell-contacting substrates. Despite their prevalence, the influence of polyelectrolyte assembly on protein structure and function is not well understood. Indeed, the recent literature includes examples of polyelectrolyte-enhanced protein stability, as well as examples of diminished stability. We report here on the conformational stability of a short, beta hairpin forming model protein, in the presence of various charged polymers of biological origin (poly(amino acids) and polysaccharides), as measured using molecular dynamics simulation and circular dichroism experiment. We find the temperature dependent extent of beta hairpin structure to vary significantly with polymer hydrophobicity and hydrogen bonding ability, and seek to understand these findings within a simple statistical mechanical lattice model. These studies lend important insight into the design of optimal polymers for diverse biomaterial applications, as well as broader questions on biomolecular (un)folding under crowded or heterogeneous conditions.
Thursday
3656239 - Surface chemistry, crystal structure, size and topography role in the albumin adsorption on TiO2 Anatase: A molecular dynamics study
05:20pm - 05:40pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 7
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
TiO2 is widely used in biomaterial implants. The topography, chemical and structural properties of titania surfaces are an important aspect to study. The size of TiO2 nanoparticles synthetized by sol–gel method can influence the responses in the biological environment, and by using appropriate heat treatments different contents of different polymorphs can be formed. Protein adsorption is a crucial step for the biological responses, involving, in particular, albumin, the most abundant blood protein. In this theoretical work, using molecular mechanics and molecular dynamics methods, the adsorption process of an albumin subdomain is reported both onto specific different crystallographic faces of TiO2 anatase and also on its ideal three-dimensional nanosized crystal, using the simulation protocol proposed in previous theoretical studies about the adsorption process on hydrophobic ordered graphene-like or hydrophilic amorphous polymeric surfaces. The different surface chemistry of anatase crystalline faces and the nanocrystal topography influence the adsorption process, in particular the interaction strength and protein fragment conformation, then its biological activity. This theoretical study can be a useful tool to better understand how the surface chemistry, crystal structure, size and topography play a key role in protein adsorption process onto anatase surface so widely used as biomaterial.
Left: initial interaction energies as a function of the number of aminoacids in contact with different material surfaces (flat graphite, curved outer surface of SWCNTs, amorphous PVA, the (0 0 -1) and the more hydrophilic (0 0 1) TiO<sub>2</sub> anatase crystallographic face. Right: final adsorption of three albumin <i>A</i>-subdomains on ideal 3D-nanocrystal of TiO<sub>2</sub> anatase.

Left: initial interaction energies as a function of the number of aminoacids in contact with different material surfaces (flat graphite, curved outer surface of SWCNTs, amorphous PVA, the (0 0 -1) and the more hydrophilic (0 0 1) TiO2 anatase crystallographic face. Right: final adsorption of three albumin A-subdomains on ideal 3D-nanocrystal of TiO2 anatase.


Thursday
3656587 - Development of photocrosslinkable Kappa-carrageenan bioink to fabricate cell-laden scaffolds with high cytocompatibility
05:40pm - 06:00pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 7
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
Bioprinting of three-dimensional (3D) cell-laden structures has great potential to bring off the need for tissue/organs for transplantation and accurate in vitro models for drug screening. The use of hydrogels biomaterials in 3D bioprinting has several advantages over synthetic materials such as printability, relevant swelling features, biocompatibility, biodegradability, good interaction with the host tissues, and have cell-binding sites that promote cell attachment, growth, differentiation, and proliferation. In the current study, we synthesized photocurable polysaccharide methacrylate-κ-carrageenan (MA-κ-CA) by covalent grafting of methacrylate moieties to the hydroxyl functional groups of κ-CA with the degree of substitution (DS) of 48 %. Hydrogels with varying concentrations of 1- 5 % (w/v) of MA-κ-CA were prepared within minutes with a curing time of 5 s per layer through 3D digital light processing (DLP) printing technology. Also, 3D hydrogel scaffolds with highly complex structures can be easily fabricated with high accuracy and reproducibility. DLP-printed MA-κ-CA hydrogels showed enhanced mechanical strength, and optimal viscosity and shear thinning behavior, demonstrating its possible application in the regeneration of soft tissues such as skin, muscles, heart, lung, liver, and for engineering other tissues/organs of specific biological functions. Furthermore, DLP-printed 3D scaffolds of bioink (MA-κ-CA with NIH3T3 and HaCaT cells) showed good cytocompatibility and proliferation of cells within the printed scaffold matrix over days.
Schematic illustration of DLP printing system with photocurable bioink solution of 2% w/v MA-κ-CA mixed with NIH/3T3 and HaCaT cells in layer-by-layer processing using DLP printer, Lumen X.

Schematic illustration of DLP printing system with photocurable bioink solution of 2% w/v MA-κ-CA mixed with NIH/3T3 and HaCaT cells in layer-by-layer processing using DLP printer, Lumen X.


Thursday
3656831 - Orthogonal strategies for biocompatible surfaces
06:00pm - 06:20pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 7
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
The interaction of synthetic materials with living systems occurs at the surface. The broadest meaning of the term “biocompatible” applies to a synthetic surface that does not perturb the complex, interconnected balance of components and their associations in living systems. However, very different strategies have been taken to render surfaces biocompatible. In the first approach, the surface is coated with functional groups designed to decrease the extent of protein adsorption to the lowest levels possible. This is typically accomplished with a coating of polyethylene glycol (PEG) or zwitterion. For both functionalities, “more is better” reasoning leads to the use of thick layers or brushes for more efficient antifouling. Alternatively, a surface may, often by accident, be an efficient “total adsorber” that adsorbs and retains a selection of species, notably albumin, from the physiological environment. The composition profile of adsorbed components matches that of the environment and therefore does not elicit a foreign-body response. This talk will present examples of the two strategies, including apparent failures of the “nonfouling” approach using zwitterions and success with an albumin-adsorbing and retaining surface.
Thursday
3657427 - Role of surface porosity in antimicrobial coatings
06:20pm - 06:40pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 7
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
The role of antimicrobial coatings has received renewed attention during the COVID-19 pandemic. In this talk, the role of porosity on surface coatings will be considered. Porosity can have a number of effects on microbial inactivation and killing, including: increasing the surface area, reducing transport time, changing evaporation, reducing diffusion time, and altering the contact area with fingers. First, I will show that coatings of the same chemistry but different porosity have different antimicrobial efficacy. Further experiments show the effect of differing surface area. The rate of droplet evaporation is also important in activating microbes, and results will show how evaporation is affected by porosity. Finally, in order for a person to become infected by a contaminated surface, the causative virus (SARS-CoV-2) must be transferred to the body. Results will be presented for the effect of porosity on the transfer
Thursday
Concluding Remarks
06:40pm - 06:45pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 7
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual

New Quantum Solutions for Quantum Systems and Devices: Quantum Excitonics
03:00pm - 06:20pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 1
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Virtual
Division/Committee: [PHYS] Division of Physical Chemistry

The third quantum revolution has now arrived and it is important to ensure the availability of computing paradigms for rigorous assessment of proposals for next generation molecular- and material- qubits and for rigor in the design of quantum algorithms which are already focusing on down-folding of high accuracy methods. Requirements include coupled-cluster reliability at computational costs associated with density-functional theory and also the ability to accurately predict all couplings between electronic-, spin-, spin-orbit, vibrational- and isotopic- degrees of freedom. This symposium will discuss the full diversity of methods to better embrace the need for such quantum diversity, and to understand how to efficiently account for both on-determinantal and multi-configurational effects.

Thursday
3661269 - Machine learning methodologies for accurate electron correlation energies and potential energy surfaces
03:00pm - 03:30pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 1
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Virtual
Studies on quantum systems impose a challenge for theoretical studies due to the compromise between accuracy and computational cost in their calculations. Machine learning methods are an approach to solve this trade-off by leveraging large data sets to train on highly accurate calculations using small molecules and then apply them to larger systems. In this study, we will discuss two machine learning projects: (1) the prediction of electron correlation energies and (2) neural network potentials for chemical reactions. To accurately predict the total correlation energy, we explore different machine learning architecture and features and discuss various trade-offs between complexity and performance. For neural network potentials, we discuss an active learning algorithm which allows for the accurate description of potential energy surfaces. Together, we believe these algorithms will allow for the accurate study of quantum devices.
Thursday
3656860 - Semi-supervised learning detects safe islands where density functional theory is applicable for chemical discovery
03:30pm - 04:00pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 1
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Virtual
Density functional theory (DFT) plays an essential role in the discovery of new molecules and materials responsible for quantum devices because of its optimal balance between accuracy and computational cost. Despite this balance, DFT can be inaccurate for strongly correlated systems (e.g. containing transition metals or stretched bonds), especially when used to predict their spin states ordering. To address this challenge, numerous multi-reference (MR) diagnostics have been developed over the years. These diagnostics aim to detect strong correlation and identify when single-reference methods(such as DFT) are insufficient for obtaining molecular properties. Despite the emergence of dozens of diagnostics, no single diagnostic has been universally predictive of MR character. Additionally, many such diagnostics are based on computationally demanding calculations (i.e., wavefunction theory, or WFT) that may also be intractable. Therefore, we aim to generate a low-cost and universal metric that measures whether a system is suitable for DFT evaluation. We generate a dataset that contains 15 MR diagnostics from multiple levels of theory on equilibrium and distorted geometries of organic molecules. We observe poor linear correlation across 15 MR diagnostics, with more expensive WFT based diagnostics outperforming the DFT based diagnostics in predicting a figure of merit for MR character. We train supervisedlearning models to predict more demanding WFT diagnostics using the DFT diagnostics along with the molecular geometries as inputs, to eliminate the cost of performing the WFT calculations. We show how a semi-supervised learning classifier unravels the hidden consensus of the 15 MR diagnostics by utilizing the distribution of the diagnostics for all data points. We demonstrate that this classifier is robust to noisy inputs and thus can achieve the same accuracy even it only sees the ML-predicted WFT diagnostics as the model inputs. Since our workflow only requires DFT calculations, we expect this data-driven decision engine to be useful in detecting “safe islands” for DFT based high-throughput computation and guiding the selection of the optimal electronic structure methods for the evaluation of new chemical systems for quantum devices in chemical discovery.
Thursday
3657819 - Designing ionic liquids to adjust the interaction and spacing of α-RuCl3 flakes
04:00pm - 04:30pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 1
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Virtual
Fault tolerance in spin propagation is a key hurdle in the development of quantum material technologies. α-RuCl3 is one candidate material to exhibit quantum spin liquids (QSL) properties and it has been hypothesized that ionic liquids (ILs) could be designed to coat the crystal, tune distances between neighboring crystals, and gate the transfer of spin states increasing the reliability and reproducibility of signals permutated through the QSL. We used molecular dynamics (MD) and periodic density functional theory (DFT) to probe the design space of ion pairs that would naturally form this gated structure between α-RuCl3 flakes. With these results, we report trends in the design and selection of IL constituents and their impact on α-RuCl3 materials. Electronic structure calculations and physical experiments on the material properties and electronic properties are ongoing.
Thursday
Intermission
04:30pm - 04:50pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 1
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Virtual

Thursday
3647627 - Molecular quantum dynamics: a quantum computing perspective
04:50pm - 05:20pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 1
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Virtual
Simulating molecular dynamics within a comprehensive quantum framework has been a long-standing challenge in computational chemistry. An exponential scaling of computational cost renders solving the time-dependent Schrödinger equation (TDSE) of a molecular Hamiltonian, including both electronic and nuclear degrees of freedom (DOF), as well as their couplings, infeasible for more than a few DOFs.
In the Born-Oppenheimer (BO), or adiabatic, picture, electronic and nuclear parts of the wavefunction are decoupled and treated separately, enabling the treatment of up to a few dozens of DOFs. However, for particular applications, such as photochemistry, the BO approximation breaks down. In this regime of non-adiabatic dynamics, solving the full molecular problem including electron-nuclear couplings becomes essential, further increasing the complexity of the numerical solution.

In this talk, I will propose a perspective on novel quantum computational algorithms, aiming to alleviate the exponential scaling inherent to the simulation of many-body quantum dynamics. In particular, we focus on the derivation and application of quantum algorithms for adiabatic and non-adiabatic quantum dynamics, which include efficient approaches for the calculation of the BO potential energy surfaces.
In a first application, I will discuss a recently introduced quantum algorithm for the evolution of a wavepacket in first quantization and exploit the potential quantum advantage of mapping its spatial grid representation to logarithmically many qubits.
For the second demonstration, I will move to the second quantization framework and review the scaling properties of two alternative time-evolution algorithms, namely a variational quantum algorithm (based on the McLachlan variational principle) and conventional Trotter-type evolution (based on a Lie-Trotter-Suzuki formula).
Both methods clearly demonstrate the potential of quantum algorithms and their favourable scaling compared to the available classical approaches. However, a clear demonstration of quantum advantage in the context of molecular quantum dynamics may require the implementation of these algorithms in fault-tolerant quantum computers, while their application in near-term, noisy quantum devices is still unclear and deserves further investigation.

Thursday
3644784 - Withdrawn
05:20pm - 05:50pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 1
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Virtual

Thursday
3656414 - Relativistic molecular quantum mechanics and application to laser cooling of polyatomic molecules
05:50pm - 06:20pm USA / Canada - Pacific - March 24, 2022 | Location: Virtual 1
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Virtual
We report recent development of relativistic exact two-component (X2C) Hamiltonians for accurate treatments of spin-orbit coupling. We discuss formulation and efficient implementation of atomic mean-field spin-orbit approaches within X2C for both perturbative and non-perturbative treatments of spin-orbit coupling. Combining the relativistic electronic-structure methods and multistate vibronic Hamiltonian, we develop a generally applicable computational approach to determine vibronic branching ratios in polyatomic molecules to the 10-5 level, including for nominally symmetry-forbidden transitions. This approach is demonstrated for metal-containing molecules, showing approximately two orders of magnitude improved sensitivity compared with the previous state of the art. This enables probing subtle molecular physics and will benefit the field of quantum computation through an informed choice of best molecules.