Structure Of Hybrid Materials Research Articles

Unveiling Noncentrosymmetric Pyridine Carboxylates from Centrosymmetric Templates through Motif Configuration Modulation in Zero-Dimensional System.

Developing approaches to induce noncentrosymmetric (NCS) frameworks through atomic-scale structural optimizations is crucial due to the growing need for new ultraviolet (UV) nonlinear optical (NLO) materials. Herein, the first two new NCS pyridine carboxylates, ZnBr(C6H3.5FNO2)2 (1) and Cd(C6H3FNO2)2(H2O)2 (2), were successfully synthesized using centrosymmetric (CS) templates and rational structural reconstructions induced by different ionic radius. Both compounds crystallize in the orthorhombic system and feature metal-centered zero-dimensional (0D) isolated clusters. Substituting the [ZnO2N2O] pyramid in the CS pyridine carboxylate with the [ZnO2N2Br] pyramid in compound 1 breaks the centrality, leading to an NCS framework with a second harmonic generation (SHG) response of 1.7 × KH2PO4 (KDP). Introducing a larger Cd2+ cation results in a trans-to-cis transition of the [MO4N2] (M = Zn, Co, and Ni in CS templates, Cd in 2) octahedra, forming a wing-shaped asymmetric 0D cluster with an SHG response of 2.1 × KDP. These findings indicate an approach that can effectively induce NCS structures of 0D organic-inorganic hybrid materials.

Controlled Construction of Surface Hybrid Structures of Zirconium Powder Assisted by Microdroplets and Photopolymerization Collaboration.

The controlled construction of hybrid material structures can effectively regulate the physical, chemical, and functional properties of materials. This work explores the feasibility of coupling microdroplets technology and photopolymerization methods to achieve controllable construction of hybrid structures on the surface of ultrafine zirconium (Zr) powder, and investigates the effects of different hybrid structures on the surface mechanical properties, thermal oxidation performance, and electrostatic safety of Zr powder. The photopolymerization reaction process of PMMA on the surface of Zr powder was analyzed, revealing the principle of accelerated photopolymerization reactions within microdroplets, which was experimentally validated. Furthermore, by altering the polymerization reaction conditions and with the assistance of hydrofluoric acid (HF), a mechanism for controlling the hybrid structures on the surface of Zr powder was proposed. The results demonstrated that the collaborative effect of microdroplets and photopolymerization methods efficiently controlled the content and structural characteristics of the PMMA coating on the surface of Zr powder. The further introduction of HF was found to adjust the morphology of the surface hybrid structures and significantly improve the thermal oxidation performance and electrostatic safety of the Zr powder. These findings provided insights into the surface property regulation of active energetic materials and paved the way for the controlled preparation of inorganic-organic hybrid materials.

Crystal Structure, Hirshfeld Surface, Vibrational Study, Optical Properties and Biological Activities of a Novel Hybrid Material 2-Methylpiperazine-1,4-Dium Tetrachlorocobaltate(II) based on DFT Calculation

Crystal Structure, Hirshfeld Surface, Vibrational Study, Optical Properties and Biological Activities of a Novel Hybrid Material 2-Methylpiperazine-1,4-Dium Tetrachlorocobaltate(II) based on DFT Calculation

A multi-material topology optimization approach to hybrid material structures with gradient lattices

In this paper, we present a novel approach for designing hybrid material structures that incorporate solid, void, and spatially-varying lattices. This approach extends the recursively defined power-law type multi-material interpolation model by incorporating additional gradient material phases. Unlike conventional models, the new extended model considers the secondary ``solid'' material phase as a type of lattice, enabling adjustment of lattice geometry and mechanical behavior with gradient control variables such as density or size. By means of numerical homogenization and interpolation, we explicitly express the effective mechanical behavior of the gradient lattice in relation to the gradient control variable. This approach enhances design freedom by allowing for flexible control of individual material volumes, and also the lower and upper bounds of gradient variables. By using implicit geometrical modeling techniques, the resulting gradient control variable field can be interpreted to create spatially-varying and smoothly-connected lattices at any arbitrary resolution. The effectiveness and flexibility of the proposed approach have been demonstrated through a series of benchmark design tests considering various lattice material types.

Oxidation-Induced Dissolution Recrystallization Structural Transformation Strategy Enhanced Nonlinear Optical Effect of Hybrid Chiral Tin Bromide Single Crystals.

In order to reveal the integrated effect of inorganic lattice structure disturbances and chiral ligands on the structure of tin halide hybrid materials, we show the synthesis, crystal growth, dissolution recrystallization structural transformation (DRST), optical properties, energy band structure, and nonlinear optical properties of a class of chiral tin bromide R/S-2-mpip[SnBr3]Br (2-mpip is 2-methylpiperazinium) and R/S-2-mpipSnBr6 for the first time. The formation of R/S-2-mpipSnBr6 in solution was interestingly caused by irreversible DRST of R/S-2-mpip[SnBr3]Br. The second-harmonic generation response of the new phase R-2-mpipSnBr6 is significantly enhanced compared to that of the initial phase R-2-mpip[SnBr3]Br. These structural transformations of chiral tin bromides reflect, to some extent, the DRST commonality of the tin halide family induced by oxidation and serve as a starting point for investigating the structural chirality and asymmetry of chiral metal hybrid halides.

Low-frequency band gap and wave attenuation mechanisms of novel hybrid chiral metamaterials

Based on the hexagonal honeycomb structure and the tri-ligament chiral honeycomb structure, this paper proposes a hybrid material structure with low-frequency elastic wave suppression below 100[Formula: see text]Hz. Based on the finite element method and Bloch’s theorem, the energy band structure was calculated, and the formation of the band gap and the wave-propagation properties of the structure were carefully studied, the wave attenuation performance of the composite structure was simulated, and the influence of material properties and geometric parameters on the width and position of the band-gap distribution was discussed. The results show that the structure can generate a good band gap in the low-frequency range of 100[Formula: see text]Hz, and the wave propagation is suppressed obviously. Demonstrating its potential in practical applications, the research in this paper provides a theoretical basis for the manufacture of low-frequency vibration damping equipment and instruments, and provides a scheme for the design of metamaterials with low-frequency band gaps.

ELECTROCHEMICAL SYNTHESIS OF HYBRID MATERIALS BASED ON POLYELECTROLYTE CHITOSAN COMPLEXES AND INVESTIGATION OF THEIR PHYSICAL AND CHEMICAL PROPERTIES

A study of the morphology, structure and elemental composition of hybrid materials on the surface of stainless steel based on polyelectrolyte complexes of chitosan with cobalt and nickel oxides, obtained using an alternating asymmetric current, was carried out. It was established by X-ray phase analysis that the main phase of the obtained hybrid materials is cobalt hydroxyisocyanate. The prospects of using the obtained hybrid materials as electrodes for supercapacitors with alkaline electrolyte are shown, while its specific capacitance at a current density of 1 A∙g-1 reaches 479 F∙g-1. The antibacterial activity of hybrid materials against gram-positive (S.aureus) and gram-negative (E.coli) microorganisms was determined. A study of corrosion-protective properties of the developed hybrid materials in a solution of 3.5 wt. % NaCl was carried out, it is shown that for the hybrid material the corrosion potential is shifted to the region of positive values compared to pure steel.

Effects of different metal centers on the structure and luminescence properties of hybrid materials

Three novel inorganic-organic hybrid materials, [PbI3(BTA-1)]n (1) (BTA-1 = N-((1H-benzotriazole-1-yl)methyl)-N,N-dimethyl ethylammonium)，[Cu2I3(BTA-2)]n (2) (BTA-2 = 1-(1H-benzotriazole-1-yl)-N,N,N-trimethylammonium carbamate) and [ZnI3(BTA-3)]n (3) (BTA-3 = 3-(1H-benzotriazole-1-yl)-N,N,N-trimethylpropane-1-ammonium), have been was prepared by a solvent volatilization method. All three complexes have been characterized by single-crystal X-ray diffraction, powder X-ray diffraction (PXRD) and thermogravimetric (TG) analysis. Based on different metal iodides, they stack in different structural modes with different cluster cores, such as [PbI6]2- in complex 1, [Cu4I6]2- in complex 2 and [ZnI3N]2- in complex 3. The fluorescence analysis show that complex 1 and 2 produced green light when the excitation wavelength was 318 nm and 328 nm, respectively. While complex 3 exhibited near white light when the excitation wavelength was 424 nm (CIE: 0.332, 0.395). It shows that complex 3 can be used as a white light emitting material for direct blue light excitation.

Thermal-mechanical-equivalent fatigue load method for mechanically fastened Hybrid-material structures

It is difficult to verify the fatigue performance of mechanically fastened hybrid-material structures under the complex environment-load spectrum. A thermal–mechanical-equivalent fatigue load method was proposed, so that the structure has the same fatigue damage distribution under the equivalent load and the original thermal–mechanical load. By considering the influence of environmental temperature on the structural fatigue performance and the dispersion of material fatigue property, the calculation model for the fatigue damage distribution of fastened structure was established. The equivalent load could be determined according to the designed tolerance value of distribution difference. The effectiveness of method was verified by 7050-T7451 aluminum alloy/CFRP laminate plate three-bolt single-lapped hybrid fastened specimens.

Crystal structure, thermal behavior and electric properties of a new semiconductor cobalt-based hybrid material

The crystals of the new organic-inorganic hybrid material, (C5H12N)2[CoBr2.73Cl1.27], were successfully synthesized by the slow evaporation method and characterized by single-crystal X-ray diffraction, thermal analysis, UV–Vis absorption and electrical measurements. This compound crystallizes in the centrosymmetric space group P21/n of the monoclinic system with unit cell parameters: a = 9.7724 (6) Å, b = 12.3920 (6) Å, c = 15.0307 (9) Å, β = 100.864(6) °, V = 1787.59(18) Å3 and Z = 4. The IR spectrum of the compound is studied, especially for the cationic vibrational part. The thermal analysis indicates that (C5H12N)2[CoBr2.73Cl1.27] is stable up to 270 °C and that it undergoes two reversible phase transitions at 152 and 187 °C and at 141 and 128 °C on heating and cooling, respectively. From UV visible gap energy value of 3 eV it can be concluded that the new mixed halide compound is a semiconductor material. The electrical behavior of (C5H12N)2[CoBr2.73Cl1.27] was studied using impedance spectroscopy in the temperature range of 323 to 403 K. According to a study on the frequency dependence of ac conductivity, the material follows Jonscher's universal dynamic law with an increase in the frequency exponent (s) as temperature increases. This behavior reveals that the conduction mechanism is the nonoverlapping small polaron tunneling (NSPT) model.

Materials and Design Approaches for a Fully Bioresorbable, Electrically Conductive and Mechanically Compliant Cardiac Patch Technology.

Myocardial infarction (MI) is one of the leading causes of death and disability. Recently developed cardiac patches provide mechanical support and additional conductive paths to promote electrical signal propagation in the MI area to synchronize cardiac excitation and contraction. Cardiac patches based on conductive polymers offer attractive features; however, the modest levels of elasticity and high impedance interfaces limit their mechanical and electrical performance. These structures also operate as permanent implants, even in cases where their utility is limited to the healing period of tissue damaged by the MI. The work presented here introduces a highly conductive cardiac patch that combines bioresorbable metals and polymers together in a hybrid material structure configured in a thin serpentine geometry that yields elastic mechanical properties. Finite element analysis guides optimized choices of layouts in these systems. Regular and synchronous contraction of human induced pluripotent stem cell-derived cardiomyocytes on the cardiac patch and ex vivo studies offer insights into the essential properties and the bio-interface. These results provide additional options in the design of cardiac patches to treat MI and other cardiac disorders.

Highly efficient and stable layered AgZnS@WS2 nanocomposite electrode as superior charge transfer and active redox sites for energy harvesting device

Transition metal dichalcogenides (TMDs) are considered to be excellent candidates in energy storage applications because of their 2D structure and astonishing electrochemical features. Still, the poor stability of these materials limits their way to becoming perfect supercapattery electrode materials. Therefore, researchers are synthesizing their hybrids with other electrode materials to minimize these drawbacks. Herein, the tungsten disulfide (WS2) nanosheets were combined with hydrothermally synthesized silver zinc sulfide (AgZnS) nanostructures to design a hybrid electrode material for high-performance energy storage devices with superior charge transfer and abundant active redox sites. The highly porous structure of AgZnS@WS2 was analyzed by BET which confirmed the enhancement in ion diffusion and the reversible redox mechanism. The composite was analyzed using SEM, XRD, RAMAN, and XPS to study its morphological, structural, and compositional properties. The effect of different electrolytes was studied to estimate the electrochemical characteristics. The AgZnS electrode, upon characterization in 1 M KOH, revealed the maximum specific capacity (Qs) of 1209.06 Cg−1 at 1.8 Ag−1. While the AgZnS@WS2 hybrid electrode exhibited the Qs of 2516.58 Cg−1 at the same current density (js) benefitting from the features of both materials. The AgZnS@WS2 hybrid electrode employed in a supercapattery revealed a maximum Qs of 388.8 Cg−1 at 1.2 Ag−1. The device delivered a maximum energy density of 86.4 Wh kg−1 and a notable power density of 4987.6 W kg−1. The superb 95 % cycle stability and strong electrochemical performance of AgZnS@WS2 are the results of the highly conductive structure and synergistic effect of hybrid material for high surface area with quick ion diffusion. The astonishing features of hybrid material are suitable and encouraging for its industrial applications as supercapattery electrode material.

Hybrid Metasurfaces of Plasmonic Lattices and 2D Materials

AbstractPlasmonic metasurfaces can significantly enhance the interaction between light and 2D materials. Hybrid structures of plasmonic lattices and 2D materials show great promise for both fundamental and practical studies because of their unprecedented ability for precise manipulation of light at the nanoscale. This review starts with an overview of the basic concepts of plasmonic lattices and optical properties of 2D materials, as well as fabrication strategies for hybrid metasurfaces. Then, the enhanced photoluminescence, quantum emission, optoelectronic detection, nonlinear process, and valleytronics in hybrid metasurfaces are summarized, and their development for nanophotonic functional devices are reviewed. Further, several compelling topics are also outlined that provide outlooks for future directions of hybrid metasurfaces such as novel structural design and high‐quality fabrication, all‐dielectric metasurfaces, dynamic metasurfaces, and plasmonic mediation of chemical reactions and physical processes. It is believed that hybrid metasurfaces of plasmonic lattices and 2D materials can open prospects for versatile platforms for light‐matter interactions and contribute to the revolutions on nanophotonic devices.

Intercalated chitosan-ionic liquid ionogel in SnO nanoplate: band gap narrow and adsorption-photodegradation process

Ionogels are a category of hybrid material containing ionic liquid stabilized by polymeric network. These composites have some applications in solid-state, energy storage devices and environmental studies. In this research, chitosan (CS), ethyl pyridinium iodide ionic liquid (IL), and ionogel (IG) consisting of chitosan and ionic liquid were used in the preparation of a SnO nanoplate (SnO-IL, SnO-CS and SnO-IG). For the preparation of the ethyl pyridinium iodide, a mixture of pyridine and iodoethane (1: 2 molar ratio) was refluxed for 24 hours. The ionogel was formed using ethyl pyridinium iodide ionic liquid in chitosan that was dissolved in acetic acid (1 % v/v). By increasing NH3∙H2O, the pH of the ionogel reached 7‐8. Then, the resultant IG was mixed with SnO in an ultrasonic bath for 1 h. The microstructure of the ionogel was involved as assembled unit via π-π, electrostatic and hydrogen bonding interactions to be three-dimensional networks. The intercalated ionic liquid and chitosan influenced the stability of the SnO nanoplates and improved band gap values. When chitosan was contained as the interlayer space of the SnO nanostructure, the resulting biocomposite formed a well-ordered flower-like SnO structure. These hybrid material structures were characterized by FT-IR, XRD, SEM, TGA, DSC, BET, and DRS techniques. The changes in the band gap values for photocatalysis applications were investigated. In the case of SnO, SnO-IL, SnO-CS, and SnO-IG, the band gap energy was 3.9, 3.6, 3.2, and 2.8 eV, respectively. The dye removal efficiency of SnO-IG was 98.5, 98.8, 97.9, and 98.4 % via the second-order kinetic model for Reactive Red 141, Reactive Red 195, Reactive Red 198, and Reactive Yellow 18, respectively. The maximum adsorption capacity of SnO-IG was 540.5, 584.7, 1501.5, and 1100.1 mg/g for Red 141, Red 195, Red 198, and Yellow 18 dyes, respectively. Also, an acceptable result (96.47 % dye removal) was obtained with the prepared SnO-IG biocomposite for dye removal from textile wastewater.

Dynamic co-assembly behaviors of polyoxometalates and giant surfactants in dual solvents

Inorganic-organic hybridization is a widely used method to develop new functional materials involving polyoxometalates (POMs), affording them with unique synergistic physical and chemical properties. As one of the core topics in hybrid materials, the study of their assembly structures is critical for the optimization of their performances.In the present work, dynamic co-assembly behaviors of several giant surfactants XPOSS-PS (X, POSS and PS denote different polar groups, polyhedral oligomeric silsesquioxane and polystyrene, respectively) and Keggin-type silicotungstic acid H4SiW12O40 (H4SiW for short) were investigated. We designed and synthesized three series of giant surfactants that possess heads bearing cationic (NPOSS-PS, N for ammonium group), neutral (DPOSS-PS, D for dihydroxyl group) and anionic charges (APOSS-PS, A for carboxylic acid group), respectively. The different charge types of POSS heads lead to different electrostatic interactions with the anionic POM clusters, resulting in different co-assembly structures in dual mixed solvents. Moreover, we found the POM's loading content and PS chain length are another two important factors that can determine the morphology of co-assembly structures. This work expands the scope of co-assembled structures of POM-based hybrid materials, and provides a platform for the study of the basic physical principles of their co-assembly behaviors.

Fabrication of hybrid covalent triazine framework-zinc ferrite spinel to uplift visible light-driven photocatalytic organic pollutant degradation.

The tunability of porous covalent triazine frameworks (CTFs) can mitigate poor photostability and rapid hole-electron recombination. Herein, an excellent improvement of visible light-driven photocatalytic pollutant degradation was achieved using a hybrid semiconductor of covalent triazine framework-zinc ferrite spinel catalysts (CTF-ZnFe2O4). The as-prepared CTF-ZnFe2O4 composites were fabricated using a facile one-pot ionothermal method. The hybrid photocatalysts were identified using X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray (SEM-EDX), X-ray photoelectron spectrometer (XPS), Brunauer-Emmett-Teller (BET), Fourier transform infrared (FTIR), and UV-visible diffuse reflection spectroscopy (UV-vis DRS) characterizations. The analysis reveals that hybridization successfully ensued and altered the crystallinity structure, morphology, surface area, and bandgap energy of hybrid material. It was found that CTF-ZnFe2O4 90:10 is very effective for the degradation of MB in a UV-vis light photocatalytic process with the efficiency of 95.4% and kobs of 0.421min-1 for degradation of 50mg/L MB with 0.5g/L dosages for 120min. Additionally, the scavenger study, effect of additional oxidants, and stability were performed for the practical application of a hybrid photocatalyst. CTF-ZnFe2O4 90:10 shows outstanding pollutant degradation in sunlight irradiation and high stability with only a 5.2% reduction after a five-times sequential recycling process. Moreover, the photocatalytic mechanism of as-prepared CTF-ZnFe2O4 was mainly influenced by [Formula: see text] radical compared to [Formula: see text] and [Formula: see text]radicals. Overall, The as-prepared CTF-ZnFe2O4 shows significant potential to be utilized for photocatalytic wastewater treatment.

High Power-Density WO3-x–Grafted Corannulene-Modified graphene nanostructures for Micro-Supercapacitors

• Micro-supercapacitors (MSCs) with reduced graphene oxide (rGO) were designed. • Restocking of rGO nanosheets was prevented with corannulene Bucky-bowls. • rGO nanosheets were modified by grafted intercalation WO 3 nanoparticles. • Double-layer capacitance of rGO nanosheets was augmented with WO 3 pseudocapacitance. • High energy-density and high power-density of MSCs were achieved. The emergence of nanotechnology and development of new methods of nanoengineering novel materials have enabled to design supercapacitors, new devices filling the niche between the high energy-density electrochemical batteries and the high power-density dry capacitors. Thanks to the nanoengineering, new devices combining the unique properties of electrochemical double-layer capacitance with high storage capability of pseudocapacitance materials could became a reality. A special niche in these applications is for micro-supercapacitors, which can drive miniature sensors and implantable biodevices, requiring fast remote charging and high energy density packed in a small volume. In this work, the micro-supercapacitors were fabricated using WO 3-x nanoparticles immobilized on rGO nanosheets to increase the carbon nanoform double-layer capacitance by adding very high pseudocapacitance of WO 3-x . To improve the attachment of WO 3 to the carbon support and enhance the graphene matrix conductance, grafting of WO 3 nuclei onto the GO defect sites was employed by electrochemical processing and nanoparticle growth, followed by the electroreduction of unprotected oxidation sites of GO to form a highly-conductive reduced graphene oxide (rGO) support. Further protection of rGO nanosheets from stacking interactions was also necessary. It was achieved by modifying graphene sheets with corannulene (CORA) which is a C 20 H 10 polyaromatic hydrocarbon (PAH) molecule forming a cup (or: Bucky bowl) structure. We have found that corannulene can efficiently separate the rGO nanosheets in more hydrophobic locations of rGO where WO 3-x nanoforms are missing. The chemical structure, morphology, and electrochemical properties of hybrid materials used for designing the micro-supercapacitor devices were characterized by Raman spectroscopy (RS), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infra-red spectroscopy (FTIR), electrochemical quartz crystal nanogravimetry (EQCN), cyclic voltammetry (CV), as well as potential-pulse and current-pulse charging/discharging characteristics. The supercapacitor properties of the proposed WO 3 ,CORA/rGO devices were favorable compared with those for mono plate graphene (MPG) and laser-induced graphene (LIG) MSCs.

Insights into the Structure of Keggin-Type Polyoxometalate-Based Organic-Inorganic Hybrid Materials: The Actual Ratio of Organic Cations to Heteropolyanions.

Polyoxometalate (POM)-based organic-inorganic hybrid materials possess versatile properties and applications; however, the ratios of organic cations to POM anions still remain to be solved. In this work, 14 POM-based organic-inorganic hybrid materials were synthesized by the precipitation, hydrothermal, and solvent-evaporation methods. These hybrid materials consisted of a wide range of quaternary ammonium and imidazolium cations with different alkyl chains and different Keggin-type heteropolyanions [i.e., phosphotungstic ([PW12O40]3-), phosphomolybdic ([PMo12O40]3-), silicotungstic ([SiW12O40]4-), and silicomolybdic ([SiMo12O40]4-) anions]. Their compositions and structures were characterized complementarily by elemental analysis, powder X-ray diffraction, single-crystal X-ray diffraction, and Fourier transform infrared spectroscopy. The actual ratios of organic cations to heteropolyanions of [PW12O40]3-, [PMo12O40]3-, [SiW12O40]4-, and [SiMo12O40]4- were found to always be 3:1, 3:1, 4:1, and 4:1, respectively, independent of the organic cations, synthesis methods, and reaction parameters. This finding demonstrates that the organic cations completely substituted the protons of the heteropolyacid precursors in the hybrid materials, which thus hardly possessed Brønsted acidity probed by the pyridine adsorption and cellulose hydrolysis reaction. Such complete substitution of the protons arose apparently from the strong noncovalent interactions between the organic cations and heteropolyanions (such as electrostatic and C-H···O interactions) in the POM-based hybrid materials.

Enhanced thermal and photo-stability of a para-substituted dicumyl ketone intercalated in a layered double hydroxide.

A ketodiacid, 4,4′-dicarboxylate-dicumyl ketone (3), has been intercalated into a Zn, Al layered double hydroxide (LDH) by a coprecipitation synthesis strategy. The structure and chemical composition of the resultant hybrid material (LDH-KDA3) were characterized by powder X-ray diffraction (PXRD), FT-IR, FT-Raman and solid-state 13C{1H} NMR spectroscopies, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), and elemental analysis (CHN). PXRD showed that the dicarboxylate guest molecules assembled into a monolayer to give a basal spacing of 18.0 Å. TGA revealed that the organic guest starts to decompose at a significantly higher temperature (ca. 330°C) than that determined for the free ketodiacid (ca. 230°C). Photochemical experiments were performed to probe the photoreactivity of the ketoacid in the crystalline state, in solution, and as a guest embedded within the photochemically-inert LDH host. Irradiation of the bulk crystalline ketoacid results in photodecarbonylation and the exclusive formation of the radical-radical combination product. Solution studies employing the standard myoglobin (Mb) assay for quantification of released CO showed that the ketoacid behaved as a photoactivatable CO-releasing molecule for transfer of CO to heme proteins, although the photoreactivity was low. No photoinduced release of CO was found for the LDH system, indicating that molecular confinement enhanced the photo-stability of the hexasubstituted ketone. To better understand the behavior of 3 under irradiation, a more comprehensive study, involving excitation of this compound in DMSO-d6 followed by 1H NMR, UV-Vis and fluorescence spectroscopy, was undertaken and further rationalized with the help of time-dependent density functional theory (TDDFT) electronic quantum calculations. The photophysical study showed the formation of a less emissive compound (or compounds). New signals in the 1H NMR spectra were attributed to photoproducts obtained via Norrish type I α-cleavage decarbonylation and Norrish type II (followed by CH3 migration) pathways. TDDFT calculations predicted that the formation of a keto-enol system (via a CH3 migration step in the type II pathway) was highly favorable and consistent with the observed spectral data.

(Invited) Computational Insights to Dielectric Hybrid Glasses Under Nanoscale Confinement for Next Generation Devices

Low and Ultra-k dielectric organosilicate glasses (OSG) are widely used in device interconnect applications such as shallow trench isolation as insulating units. However, the process of gap filling between conducting units has been challenging. One of the challenges is related to the undesired formation of nanovoids in the low-k dielectric material confined inside the trench geometry. Importantly, the effects of such nanoscale device constraints on the structure and mechanical reliability of low-k dielectric hybrid materials are not very well understood. To close this lack of understanding and guide the related experimental efforts we performed molecular dynamics simulations where we explore the role of the molecular structure and connectivity of different low-k dielectric OSG precursors under nanoscale confinement, and predict the resulting elastic and fracture properties. We demonstrated that hyperconnected OSG precursors with aromatic rings, such as the 1,3,5-benzene molecule, pack more homogenously under confinement leading to smaller nanovoids and better mechanical reliability compared to conventionally bridged OSG precursors, such as the ethylene bridged Et-OCS molecule.