Acid Vapor Research Articles

Design for a Solid‐State Luminescent Sensor through Photo‐Induced Electron Transfer Based on Pyrene‐Modified o‐Carborane

Aryl‐tethered o‐carboranes have attracted attention as a platform for obtaining functional solid‐state luminescent materials with stimuli‐responsiveness. To extend versatility and applicability for advanced sensing technologies, it is essential to establish new mechanisms for regulating solid‐state luminescent properties. In this study, we demonstrate the regulation of solid‐state luminescent properties of the modified o‐carborane through photo‐induced electron transfer. We synthesized the triad based on o‐carborane modified with pyrene as a luminophore from intermolecular charge transfer and diethylaniline as a quencher. In the pristine solid state, significant emission was hardly observed due to emission quenching through photo‐induced electron transfer, while intense emission was recovered by acid vapor fuming for protonation at the diethylaniline moiety. Moreover, we confirmed that reversible changes underwent by amine vapor fuming. These results mean that solid‐state luminescent properties of o‐carborane can be controlled by the commodity photochemical process according to the molecular design.

Limits to dynamic range in GHz-THz single-dish planetary spectra

Abstract When bright solar-system objects are observed by GHz-THz regime telescopes, off-axis signals bounce around locally and re-enter the signal path with a time delay, causing sinusoidal ripples in output spectra. Ripples that are unstable over time are challenging to remove. A typical detection limit for planetary spectral lines is a fraction ∼10−3 of continuum signal, restricting searches for minor atmospheric trace-gases. Modern wideband spectra of Venus demonstrate a plethora of effects, at three example telescopes spanning nearly a factor-of-50 in frequency. Characterisation of instrumental effects as families of pure sine-waves via Fourier-analysis is shown to improve dynamic-range by factors of a few. An example upper limit on sulphuric acid (H2SO4) vapour in Venus’ mesosphere, from fully-automated data-cleaning of a 3.5 GHz band containing 10 line components, goes as deep as the best previously-published limit. The most challenging cases are searches for single lines of width comparable to ripple periods. Traditional polynomial-fitting approaches can be deployed to test for false positives, to demonstrate robustness at a level of zero ”fake lines” in >1000 comparisons. Fourier-based data-cleaning avoids subjectivity and can be fully automated, and synthetic spectra can be injected before processing to test to what degree signals are lost in cleaning. An ideal robustness strategy is mitigation at the data-acquisition stage, e.g. using slow drifts in target-velocity with respect to the telescope to isolate a planetary line from a quasi-static instrumental ripple pattern.

Vapor-Solid Interface Synthesis of Highly Crystalline Covalent Triazine Frameworks for Use as Efficient Photocatalysts.

Harsh synthetic conditions for crystalline covalent triazine frameworks (CTFs) and associated limitations on structural diversities impede not only further development of functional CTFs, but also practical large-scale synthesis. Herein, a mild and universal vapor-solid interface synthesis strategy is developed for highly crystalline CTFs employing trifluoromethanesulfonic acid vapor as catalysts. A series of highly ordered simple and functional CTFs (CTF-TJUs) can be facilely produced. In particular, the porphyrin-involved functional CTF (CTF-TJU-Por1) with high crystallinity is synthesized for the first time via this universal approach. The mechanism of vapor-catalyzed trimerization of nitrile monomers is thoroughly investigated through semi in situ characterizations. As a proof of concept, the photocatalytic performance of synthesized CTFs for water splitting is evaluated. CTF-TJU-133 exhibits significantly greater photocatalytic rates for hydrogen (4.35µmolh-1) and oxygen (2.18µmolh-1) evolutions during overall water splitting under visible light irradiations compared to other CTF-TJUs, representing one of the highest values among reported CTF photocatalysts. Further studies reveal that enhanced photocatalytic performance of CTF-TJU-133 results from optimized band structure, extended visible-light absorption, and high carrier separation efficiency. This study provides a promising strategy to synthesize various simple and functional CTFs, which significantly enriched diversities of CTF family for different application purposes.

Acid Sensors Based on Luminochromism of Solid‐State Excimer Emission of Pyrene‐Modified Polyhedral Oligomeric Silsesquioxane

To obtain solid‐state fluorescence sensors, it is essential to simultaneously obtain solid‐state emission and stimuli‐responsiveness. In this research, the modified polyhedral oligomeric silsesquioxane (POSS) tethered with pyrenes was synthesized and we confirmed that both demands for developing solid‐state fluorescence sensors can be satisfied. The POSS derivative exhibited strong emission even in the solid state. In particular, we found that exposure of the POSS films to trifluoroacetic acid vapor resulted in a significant red‐shift of the peak wavelength of the emission band. Excitation spectroscopy and comparison with model compounds suggest that this significant red‐shift should be attributable to the formation of static excimer, meaning a preformed dimer in the ground state induced by protonation of the secondary amino groups. These results indicate that POSS is a promising scaffold for a solid‐state fluorescence sensor.

Repurposing trityl-substituted triphenylamine-based polyimides for gas separation membranes by blending with a fluorinated polyimide

In the attempt to develop gas separation membranes by reusing polymers with no film-forming ability but with great potential for this purpose, blending has been approached as a simple, time- and cost-effective strategy. Herein, blends of trityl-substituted triphenylamine (TTA)-based polyimides and a fluorinated polyimide (6F-PI) were involved to prepare dense membranes by drop-casting technique. The two blend components involved in variable amounts led to different film morphologies with a strong impact on most blends' properties and gas separation performance. According to optical microscopy, SEM, AFM, and FTIR investigations, the blend series containing hexafluoroisopropylidene (6F) groups in both polyimide components proved to be fully miscible at the molecular levels. When a single 6F-based component was integrated into the blend, the polymers proved to be compatible, but only partially miscible, with a two-phase structure, in which 6F-PI wrapped around the TTA-PI growth fibrillar domains. However, all blends displayed a single glass transition and FTIR bands which do not sum the ones of the polymer components, as well as a high thermal stability, close to that of 6F-PI. Regardless their miscibility level, all blends behaved as classical polyimide films, with good mechanical properties and chemical resistance to corrosive media like acid vapors or basic solutions. The blend composition and diimide structure of TTA-PI little affected the dielectric behavior, unlike the gas separation performance that strongly depended on these characteristics. The higher amount of 6F groups in the miscible blends endowed the membranes with superior permeability and selectivity, allowing in some cases to surpass the trade-off rule. Generally, the gas permeability decreased with the increase of TTA-PI content, with some exceptions. The low intermolecular interfacial interactions promoted by TTA-PI were found to be beneficial to preserve a good selectivity of gas molecules with a small kinetic diameter (He, CO2) though their permeability is lost. The gas permeability changes as a function of the blend composition and structure were mostly due to changes in the solubility coefficient and less from gas diffusion capability, at least for CO2 and N2.

Flexible organic crystals with multi-stimuli-responsive CPL for broadband multicolor optical waveguides.

Flexible organic crystals, capable of transmitting light and responding to various external stimuli, are emerging as a new frontier in optoelectronic materials. They hold immense potential for applications in molecular machines, sensors, displays, and intelligent devices. Here, we report on flexible organic crystals based on single-component enantiomeric organic compounds, demonstrating multi-stimuli-responsive circularly polarized light (CPL). These crystals exhibit remarkable elasticity, responsiveness to light and acid vapors, and tunable circularly polarized optical signals. Upon exposure to acid vapors, the fluorescence of the crystals shifts from initial yellow emission to green emission, attributable to the protonation-induced inhibition of excited-state intramolecular proton transfer. Under UV irradiation, the fluorescence emission undergoes a red-shift, resulting from the molecular transformation from an enol configuration to a ketone configuration. Notably, both processes are reversible and can be restored under daylight. The integration of reversible fluorescence changes under light and acid vapors stimuli, CPL signals, and flexible optical waveguides within a single crystal paves the way for the application of organic crystals as all-organic chiral functional materials.

A Subtractive Method to Chemically Pattern Liquid Metal for Stretchable Circuits

AbstractAdvancements in biomedical research have spurred the development of stretchable electronic devices. While soft insulators are readily available, soft conductors with metal‐like electrical conductivity are rare. Gallium and its alloys, being nontoxic and intrinsically stretchable, are potentially ideal solutions. However, current additive liquid metal (LM) patterning methods face limitations in achieving high‐throughput, high‐resolution, and high‐density LM wiring. Here, a subtractive LM patterning method is developed to meet all these requirements simultaneously. The innovative method involves parallel filling a single continuous microfluidic mesh network with LM that short‐circuits all the pins and pads of a circuit, followed by parallel cutting of the unwanted short‐circuited interconnections using hydrochloric acid (HCl) vapor. Cutting locations are pre‐defined by designing narrower intersecting channels, leveraging capillary force for precise filling and cutting. The process is characterized using a multidimensional parametric study with varying LM line widths and HCl concentrations, and in situ impedance measurements to assess insulation performance. To showcase its high‐throughput capabilities, a mock circuit is used to successfully generate complex LM interconnects that connected hundreds of electrical pads. Finally, a stretchable LM circuit with a micro‐LED array is fabricated to demonstrate the practical application of this technology for massively parallel wiring in stretchable electronics.

Analyte-dependent Rabi splitting in solid-state plexcitonic sensors based on plasmonic nanoislands strongly coupled to J-aggregates

A key challenge in the field of plexcitonic quantum devices is the fabrication of solid-state, device-friendly plexcitonic nanostructures using inexpensive and scalable techniques. Lithography-free, bottom-up nanofabrication methods have remained relatively unexplored within the context of plexcitonic coupling. In this work, a plexcitonic system consisting of thermally dewetted plasmonic gold nanoislands (AuNI) coated with a thin film of J-aggregates was investigated. Control over nanoisland size and morphology allowed for a range of plasmon resonances with variable detuning from the exciton. The extinction spectra of the hybrid AuNI/J-aggregate films display clear splitting into upper and lower hybrid resonances, while the dispersion curve shows anti-crossing behavior with an estimated Rabi splitting of 180 eV at zero detuning. As a proof of concept for quantum sensing, the AuNI/J-aggregate hybrid was demonstrated to behave as a plexcitonic sensor for hydrochloric acid vapor analyte. This work highlights the possibility of using thermally dewetted nanoparticles as a platform for high-quality, tunable, cost-effective, and scalable plexcitonic nanostructures for sensing devices and beyond.

Conservation Issues Related to Numismatics Collections– A Brief Study

This article looks at the numismatics collection housed in museums and attempts to define various concerns that factor in their deterioration. Numismatics collections provide one of the most fascinating contexts of studying history and are a valued source in gaining insights into the bygone eras. While metal objects are considered relatively stable however, they are prone to corrosion and deterioration when exposed to extreme humidity levels, acidic vapours, pollutants and chemically unstable materials. This article discusses various factors that should be considered while deciding on the display and storage materials where these objects are eventually going to be housed in a museum. The preventive care that these objects require can help in arresting their dissolution and preserve them for the next generation

Mono and binuclear Pt(II) complexes incorporated with NHC ligands: syntheses, photophysical properties, and acid vapor responses

Three mononuclear complexes (PtL1H, PtL2H, and PtL3H) and one binuclear complex (Pt2L1) have here been prepared using the bis-carbene ligand of 1,3-propylene-bis(1,3-dihydro-3-butyl-2H-imidazol-2-ylidene) and one of three rigid planar ligands of dibenzo[f,h]quinoxaline (L1H2), dibenzo[a,c]phenazine (L2H2), and tribenzo[a,c,i]phenazine (L3H2). These four complexes were fully characterized by nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HRMS), and elemental analyses. Moreover, the two binuclear complexes Pt2L2 and Pt2L3 could not be isolated, but Pt2L3 was isolated and characterized by single-crystal X-ray diffraction (XRD). Complexes PtL1H, PtL2H, and Pt2L1 exhibited phosphorescence in N2-degassed dichloromethane (DCM) solution at 563 nm, 656 nm, and 624 nm, respectively. Also, Pt2L1 exhibited triplet emission at 553 nm in a 2 wt% PMMA film, with the highest Ф of 63 % and τ of 23.8 μs. Moreover, complexes PtL1H and Pt2L1 were deposited on quartz plates to monitor formic acid vapor and acetic acid vapor. The plates that were covered with PtL1H exhibited phosphorescent quenching in both formic acid and acetic acid. However, the plates that were covered with Pt2L1 did only show a prompt response to formic acid, but were not sensitive to acetic acid.

Linear Non-benzenoid Isomer of Acene Fusing Chrysene with Azulene Units.

Non-benzenoid polycyclic aromatic hydrocarbons (PAHs) have received considerable attention owing to their distinctive optical and electrical properties. Nevertheless, the synthesis and optoelectronic application of non-benzenoid PAHs remain challenging. Herein, we present a facile synthesis of linear non-benzenoid PAH with an armchair edge, diACh, by fusing chrysene with two azulene units. We systematically investigated the optical and electrical properties, which were also compared to its isomers, including benzenoid and non-benzenoid zigzag edge isomers. diACh exhibits global aromaticity, good planarity, and suitable highest occupied molecular orbital/lowest unoccupied molecular orbital energy levels. The protonation of diACh in solution successively forms a stable tropylium cation and dication. Moreover, the neutral, cationic, and dicationic states of diACh can be transformed with remarkable reversibility during the protonation-deprotonation process, as confirmed by ultraviolet-visible absorptions, fluorescence spectra, 1H nuclear magnetic resonance, and theoretical calculations. Additionally, we fabricate p-type organic field-effect transistor (OFET) devices based on diACh with hole mobility up to 0.026 cm2 V-1 s-1, and we further develop OFET-based acid vapor sensors with good sensitivity, recyclability, and selectivity. These findings underscore the unique properties of linear non-benzenoid PAHs with an armchair edge engendered by the fusion of azulene with the acene backbone, showcasing prospective applications in organic optoelectronics.

A novel macroporous carboxymethyl chitosan/sodium alginate sponge dressing capable of rapid hemostasis and drug delivery

Carboxymethyl chitosan (CMCS) and sodium alginate (SA), which are excellent polysaccharide-based hemostatic agents, are capable of forming polyelectrolyte complexes (PEC) through electrostatic interactions. However, CMCS/SA PEC sponges prepared by the conventional sol-gel process exhibited slow liquid absorption rate and poor mechanical properties post-swelling. In this work, a novel strategy involving freeze casting followed by acetic acid vapor treatment to induce electrostatic interactions was developed to fabricate novel PEC sponges with varying CMCS/SA mass ratios. Compared to sol-gel process sponge, the novel sponge exhibited a higher density of electrostatic interactions, resulting in denser pore walls that resist re-gelation and swelling according to FTIR, XRD, and SEM analyses. Additionally, the liquid absorption kinetics, as well as compression and tension tests, demonstrated that the novel sponge had significantly improved rapid blood absorption capacity and mechanical properties. Furthermore, in vitro coagulation and drug release studies showed that the novel sponge had a lower blood clotting index and clotting time, along with a slower drug release rate after loading with berberine hydrochloride, showcasing its potential as a rapid hemostatic dressing with controlled drug release capabilities.

Donor‐Acceptor‐Based Conjugated Fluorescent Probes for Volatile Acid Detection

AbstractStimuli‐responsive materials based on π‐conjugated donor‐acceptor systems have great potential for sensing applications in solution and solid state. The photophysical properties of an oligo(p‐phenylenevinylene) series consisting of five push‐pull type molecules were systematically investigated to switch their absorption and emission properties by using trifluoroacetic acid as a specific external analyte. During the trifluoracetic acid sensing, the terminal pyridine units of the molecules undergo the protonation and lead to the broader absorption band at a longer wavelength region owing to the π‐π* characteristics of molecules. Upon exposing solid samples to the trifluoracetic acid vapors, the initial color of solid samples changed from yellow to orange for three‐ring system‐based molecules and brick red to wine red color for five‐ring system‐based molecules with the shifting of emission band to the longer wavelength region. Furthermore, exposing the trifluoracetic acid‐fumed solid samples to triethylamine vapors, the color of the solid samples reverted to their original colors and emission properties. The DFT analysis indicated a decreased energy band gap for the protonated molecules compared to the neutral molecules, suggesting a redshift in both the absorption and emission spectra of the protonated molecules. Thus, all the molecules of an Oligo(p‐phenylenevinylene) series can be utilized effectively for volatile acid detection.

In Situ ATR-FTIR Studies on the β-Sheet Formation of Native and Regenerated Bombyx mori Silk Material in Solution and Its Potential for Drug Releasing Coatings.

Dynamic attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy at both solutions and coatings of a semicrystalline silk material derived from Bombyx mori was applied to monitor the β-sheet conformation, which is known to correlate with silk protein crystallinity. The secondary structure-sensitive Amide I band was analyzed. Two silk protein samples were studied: native-based silk buffer fibroin (NSF) was extracted from silk glands and regenerated silk fibroin (RSF) was extracted from degummed cocoons. Solutions of both NSF and RSF at 2 mg/mL featured low initial β-sheet contents of 5-12%, which further increased to 47-53% after 24 h. RSF and NSF solutions at 23 mg/mL also featured low initial β-sheet contents of 9-10%, which yet only slightly increased to 16-17% after 24 h. Coatings deposited from RSF solutions showed high surface integrity (Q > 99%) after rinsing in mineralized water, enabling interfacial drug delivery applications. RSF coatings were post-treated with either formic acid (FA) or pure methanol (MeOH) vapor to showcase inducibility of crystalline domains in RSF coatings. Such coatings were loaded with the model antibiotic drugs tetracycline (TCL) and streptomycin (STRP), and the sustained release of TCL was followed in contact with (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) (HEPES) buffer. RSF/TCL coatings post-treated with formic acid (FA) vapor followed by methanol (MeOH) vapor showed a significantly lower (52%) initial burst of rather hydrophobic TCL compared to untreated RSF/TCL coatings (72%), while no such significant release difference was observed for hydrophilic STRP. This was rationalized by a specific interaction between nonpolar TCL and hydrophobic crystalline RSF domains.

Sintering of Cu particles baked by formic acid vapor for Cu–Cu low temperature bonding

Sintering of Cu particles baked by formic acid vapor for Cu–Cu low temperature bonding

Metal-Organic Framework on Fullerene (MOFOF) as a Hierarchical Composite by the Integration of Coordination Chemistry and Supramolecular Chemistry.

There is a synergy between coordination chemistry and supramolecular chemistry that has led to the development of innovative hierarchical composites with diverse functionalities. Here, we present a novel approach for the synthesis and characterization of a metal-organic framework on fullerene (MOFOF) composites, achieved through the integration of coordination chemistry and supramolecular chemistry principles. The hierarchical nature of the MOFOF harnesses the inherent properties of metal-organic frameworks and fullerenes. The two-step synthesis procedure involves controlled assembly of fullerenes as tube-like nanostructures (fullerene nanotube: FNT), their surface functionalization, and the on-surface growth of the MOF (in this case, ZIF-67). The method permits the precise tuning of morphology, effective distribution of MOF-on-FNT, and tight compositional control. The materials were comprehensively structurally characterized using electron microscopy, spectroscopic techniques, and other methods to elucidate the unique features and interactions within the MOFOF composites. The main findings reveal that the novel synthesis and characterization of MOFOF composites demonstrate the successful integration of coordination chemistry and supramolecular chemistry for the designing and fabricating of advanced hierarchical composites with tailored properties, including micro- and mesopore channels, interfacial facets, and defect sites. These properties are expected to lead to numerous potential applications such as gas storage and separation, catalysis, sensing, energy storage, and environmental remediation. However, only the capability of acid vapor sensing was tested and is described here.

Reversible electronic modulation of polydiacetylenes for sensing in dynamic conditions

AbstractPolydiacetylenes (PDAs) are renowned for their exceptional optical properties intricately linked to the polymer conformation, yet they exhibit poor conductivity in their undoped state. Despite this drawback, PDAs have garnered significant interest as sensing materials owing to their ability to undergo colorimetric shifts from blue to red in response to external stimuli. However, the irreversible nature of this transition has limited their utility in dynamic environments. In this study, we augment the sensing capabilities of PDA films beyond their irreversible optical response by inducing a reversible electronic response through conductivity modulation. We investigated polyamine‐substituted PDAs with enriched hydrogen‐bonding interaction sites for the concurrent changes in colorimetry and conductivity upon acetic acid (AA) vapor exposure. Coated on a flexible interdigitated electrode (IDE), we monitor the conductivity change throughout the blue‐to‐red phase transition. Remarkably, AA molecules act as dopants, significantly amplifying the system's conductivity. Although the PDA coating retains its red phase at postdopant removal, the electronic response reverts to its initial state, demonstrating reversibility. This reversible electronic response offers invaluable real‐time insights into the specific triggers within dynamic environments, underscores the adaptability of responsive conjugated polymers, and highlights a promising avenue for their utilization in various sensing and monitoring applications.

Pore-Specific Anisotropic Etching of Zeolitic Imidazolate Frameworks by Carboxylic Acid Vapors.

Anisotropic etching is a powerful way to customize metal-organic frameworks with advanced nanostructures, but it is still in its infancy. Herein, we proposed an unprecedented etching strategy that created anisotropic hollow structures in various zeolitic imidazolate framework (ZIF) nano/single crystals via pore-specific carving. The etching occurred through a newly discovered gas-solid reaction where carboxylic acid vapors bind with ligands in ZIFs at room temperature to form ionic liquid (IL). A series of experiments were conducted to decode the origin of anisotropy and the "hollowing out" effect. We found that large pore openings on {111} facets provide access for the entry of carboxylic acid vapors and the outflow of the IL, resulting in pore-dependent anisotropy features. The unique "etching after adsorption" mechanism and the adsorption capacity of the IL enable acid vapors to hollow out nanocrystals and even single crystals. By altering carboxylic acids and ligands in ZIFs, the etching process can be precisely tuned from the inside out or the outside in. This new method demonstrates broad universality and brings unprecedented morphologies and complexities. It may offer great opportunities for achieving purposeful modification of ZIFs and the rational construction of intricate architectures.

High optical contrast, dual-responsive, wearable photochromic fibers for smart textile engineering

Smart textiles exhibiting responsiveness to external light stimuli show a great scope of applications in personalized decorations and intelligent wearable devices, among others. It's both rewarding and challenging to build wearable indicators based on fibers with high contrast and versatility to monitor the state of the external environment while maintaining good conformability and breathability for practical use. Here, we have integrated spiropyran photochromic compound (SP) into the spinning solution with polyvinyl alcohol (PVA) and aqueous polyurethane (WPU), and developed fibers by wet spinning featuring photochromic and photofluorescent dual outputs. Under UV and visible light illumination, the fibers demonstrate significant contrast optical signals, rapid color switching (4 s), long retention duration (7.5 h), as well as good cycling stability (20 times). The photochromic fibers can be used in the form of photochromic wristbands or embroidered on various textiles as flexible wearable UV indicators. Furthermore, the UV-induced fibers also produce pertinent color changes when subjected to acidic and alkaline vapors. We envision that the as-prepared fibers present promising applications in environmental acidity detection and multi-stimulus responsive materials.

Precise arraying of perovskite single crystals through droplet-assisted self-alignment.

Patterned arrays of perovskite single crystals can avoid signal cross-talk in optoelectronic devices, while precise crystal distribution plays a crucial role in enhancing device performance and uniformity, optimizing photoelectric characteristics, and improving optical management. Here, we report a strategy of droplet-assisted self-alignment to precisely assemble the perovskite single-crystal arrays (PSCAs). High-quality single-crystal arrays of hybrid methylammonium lead bromide (MAPbBr3) and methylammonium lead chloride (MAPbCl3), and cesium lead bromide (CsPbBr3) can be precipitated under a formic acid vapor environment. The crystals floated within the suspended droplets undergo movement and rotation for precise alignment. The strategy allows us to deposit PSCAs with a pixel size range from 200 to 500 micrometers on diverse substrates, including indium tin oxide, glass, quartz, and poly(dimethylsiloxane), and the area can reach up to 10 centimeters by 10 centimeters. The PSCAs exhibit excellent photodetector performance with a large responsivity of 24 amperes per watt.