Heterocycle- and Amine-Free Electrochromic and Electrofluorochromic Molecules for Energy-Saving See-Through Smart Windows and Displays.

Electrochromic (EC) smart windows are an elegant alternative to dusty curtains, blinds, and traditional dimming devices. The EC energy storage smart windows and displays received remarkable attention in the optoelectronic industry as they hold promise for high energy efficiency, low power consumption, reversibility, and swift response to stimuli. However, achieving these properties remains challenging. Moreover, most EC molecules do not exhibit electrofluorochromism, which is highly essential for smart displays because its EC property can modulate the solar heat entering the building, and its electrofluorochromic (EFC) aspects can create lighting during the night. In this work, a structure-property relationship is utilized to develop new electrochromes that can store the injected charge, and these molecules indeed exhibit electrofluorochromism. The compounds are synthesized from tetrabenzofluorene with two aromatic acceptor units, and avoids the use of widely studied heterocycles and amine derivatives. The electrochromes switches from yellow to dark hue in solution, solid, and gel state. The compounds display exceptional electrochemical stability and reversibility in 1000 cycles and capacity retention of 93-100 % in 300 charging-discharging cycles. The proof-of-concept device fabrication of the self-dimming EC smart window presented here demonstrates that it can furnish visual comfort, modulate transmitted light and glare, and reduce energy usage.

"Bottom-up" self-assembly and "cold crystallization" of butterfly shaped tetrabenzofluorene molecules.

Butterfly-shaped tetrabenzo[a,c,g,i]fluorene (TBF)-based molecules (1 and 2) were designed, synthesized and well characterized using various spectroscopic techniques. The single crystal X-ray structure of 1 shows the presence of intermolecular 3-D π-π stacking interaction and unprecedented "cold crystallization" in polycyclic aromatic molecules. We report for the first time, the "bottom-up" self-assembly of TBF based organic molecules. The supramolecular studies reveal the formation of vesicles and cuboid-shaped nanocrystals in THF-water and toluene solution, respectively.

No More HF: Teflon-Assisted Ultrafast Removal of Silica to Generate High-Surface-Area Mesostructured Carbon for Enhanced CO2 Capture and Supercapacitor Performance.

An innovative technique to obtain high-surface-area mesostructured carbon (2545 m(2) g(-1)) with significant microporosity uses Teflon as the silica template removal agent. This method not only shortens synthesis time by combining silica removal and carbonization in a single step, but also assists in ultrafast removal of the template (in 10 min) with complete elimination of toxic HF usage. The obtained carbon material (JNC-1) displays excellent CO2 capture ability (ca. 26.2 wt % at 0 °C under 0.88 bar CO2 pressure), which is twice that of CMK-3 obtained by the HF etching method (13.0 wt %). JNC-1 demonstrated higher H2 adsorption capacity (2.8 wt %) compared to CMK-3 (1.2 wt %) at -196 °C under 1.0 bar H2 pressure. The bimodal pore architecture of JNC-1 led to superior supercapacitor performance, with a specific capacitance of 292 F g(-1) and 182 F g(-1) at a drain rate of 1 A g(-1) and 50 A g(-1) , respectively, in 1 m H2 SO4 compared to CMK-3 and activated carbon.

Redox-Active Metal-Organic Frameworks: Highly Stable Charge-Separated States through Strut/Guest-to-Strut Electron Transfer.

Molecular organization of donor and acceptor chromophores in self-assembled materials is of paramount interest in the field of photovoltaics or mimicry of natural light-harvesting systems. With this in mind, a redox-active porous interpenetrated metal-organic framework (MOF), {[Cd(bpdc)(bpNDI)]⋅4.5 H2 O⋅DMF}n (1) has been constructed from a mixed chromophoric system. The µ-oxo-bridged secondary building unit, {Cd2 (µ-OCO)2 }, guides the parallel alignment of bpNDI (N,N'-di(4-pyridyl)-1,4,5,8-naphthalenediimide) acceptor linkers, which are tethered with bpdc (bpdcH2 =4,4'-biphenyldicarboxylic acid) linkers of another entangled net in the framework, resulting in photochromic behaviour through inter-net electron transfer. Encapsulation of electron-donating aromatic molecules in the electron-deficient channels of 1 leads to a perfect donor-acceptor co-facial organization, resulting in long-lived charge-separated states of bpNDI. Furthermore, 1 and guest encapsulated species are characterised through electrochemical studies for understanding of their redox properties.

The morphology dependent electrocatalytic activity of Ir nanostructures towards oxygen reduction.

Iridium nanostructures with different morphologies are synthesized by a simple, environmentally friendly approach in aqueous media under mild conditions. The morphology dependent electrocatalytic activity of Ir nanochains and nanoparticles towards oxygen reduction reaction (ORR) has been demonstrated in both acidic and alkaline media. Comparative electrochemical studies reveal that nanochains exhibit significantly enhanced ORR activities in both acidic and alkaline media as compared with nanoparticles, as a result of the continuous structure of interconnected particles. The mechanism of oxygen reduction on Ir nanostructures predominantly follows a four-electron pathway in alkaline and acidic solutions. Excellent stability and good selectivity towards methanol tolerance are reported.

Hierarchical Self-Assembly and Aggregation-Induced EmissionEnhancement in Tetrabenzofluorene-based Red Emitting Molecules.

The newly synthesized chiral active [5]helicene-like tetrabenzofluorene (TBF) based highly red-emitting molecules exhibit flower-like self-assembly. These molecules display photophysical and structural properties such as intramolecular charge transfer, dual state emission, large fluorescence  quantum yield, and solvatochromism. In TBFID, the indandione functional group attached on both sides as the terminal group offers an A-D-A push-pull effect and acts as a strong acceptor to cause more redshift in solution as well as in solid state as compared to TBFPA (TBF with benzaldehyde functional group in terminal position). The self-assembly studies of TBFID demonstrate the aggregation-induced emission enhancement (AIEE) attributed to the restriction of intramolecular rotation at the aggregated state. Furthermore, TBFID shows high quantum yield and intense red emission, making the molecule fit for organic light-emitting diodes (OLED) and bioimaging applications.

ExBox: a polycyclic aromatic hydrocarbon scavenger.

A template-directed protocol, which capitalizes on donor-acceptor interactions, is employed to synthesize a semi-rigid cyclophane (ExBox(4+)) that adopts a box-like geometry and is comprised of π-electron-poor 1,4-phenylene-bridged ("extended") bipyridinium units (ExBIPY(2+)). ExBox(4+) functions as a high-affinity scavenger of an array of different polycyclic aromatic hydrocarbons (PAHs), ranging from two to seven fused rings, as a result of its large, accommodating cavity (approximately 3.5 Å in width and 11.2 Å in length when considering the van der Waals radii) and its ability to form strong non-covalent bonding interactions with π-electron-rich PAHs in either organic or aqueous media. In all, 11 PAH guests were observed to form inclusion complexes with ExBox(4+), with coronene being the largest included guest. Single-crystal X-ray diffraction data for the 11 inclusion complexes ExBox(4+)⊂PAH as well as UV/vis spectroscopic data for 10 of the complexes provide evidence of the promiscuity of ExBox(4+) for the various PAHs. Nuclear magnetic resonance spectroscopy and isothermal titration calorimetric analyses of 10 of the inclusion complexes are employed to further characterize the host-guest interactions in solution and determine the degree with which ExBox(4+) binds each PAH compound. As a proof-of-concept, a batch of crude oil from Saudi Arabia was subjected to extraction with the water-soluble form of the PAH receptor, ExBox·4Cl, resulting in the isolation of different aromatic compounds after ExBox·4Cl was regenerated.

Morphology dependent oxygen reduction activity of titanium carbide: bulk vs. nanowires.

Titanium carbide (TiC) possesses fascinating properties like high electrical conductivity and high mechanical strength coupled with high corrosion resistance and stability in acidic and alkaline environments. The present study demonstrates the tunability of mechanistic aspects of oxygen reduction reaction (ORR) using TiC nanostructures. One dimensional TiC nanostructures (TiC-NW) have been synthesized using a simple, hydrothermal method and used as a catalyst for ORR. Shape dependent electroactivity is demonstrated by comparing the activity of TiC-NW with its bulk counterparts. Comparative studies reveal higher ORR activities in the case of 1D TiC-NW involving ~4 electrons showing efficient reduction of molecular oxygen. Excellent stability and high methanol tolerance with good selectivity for ORR is reported.

Epidemiology of COVID-19 and the Utility of Cycle Threshold (Ct) Values in Predicting the Severity of Disease.

OBJECTIVES: Advanced molecular diagnostic methods like real-time polymerase chain reaction (PCR) play a vital role in the early recognition of viral infections, including the coronavirus disease 2019 (COVID-19). Therefore, in the context of the recent COVID-19 pandemic, this study aimed to determine the correlation of cycle threshold (Ct) values with symptoms in COVID-19-positive patients. MATERIALS AND METHODS: A retrospective study was conducted in a virus research diagnostic laboratory (VRDL) at a COVID-19-dedicated tertiary care hospital in South India. A total of 5563 COVID-19-positive patients were analyzed for symptom spectrum and duration of illness with Ct values of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). RESULTS: Around 80% (n= 4401) of the patients were symptomatic and the rest were asymptomatic. Among the symptomatic patients, fever (66%) was the most common symptom. About 44% of symptomatic patients had a low Ct value (Ct ≤ 24). There was a significant difference in symptoms among patients with low, medium, and high Ct values. In the subpopulation of symptomatic patients analyzed for the association of Ct value and duration of illness, the mean duration of illness was three days and almost 88% of the patients were tested within five days of onset of symptoms. It has been observed that a shorter duration of illness lowers the Ct values. A significant association was seen between the mean Ct value and days since symptom onset (p-value = 0.016). CONCLUSION: Most of the symptomatic patients had lower Ct values in comparison to the asymptomatic patients. A significant association between low Ct values and the duration of symptoms observed in our study explains the viral dynamics, i.e., higher viral shedding at the onset of symptoms and declines thereafter.

Molecular gauge blocks for building on the nanoscale.

Molecular gauge blocks, based on 1-7, 9-11 paraxylene rings, have been synthesized as part of a homologous series of oligoparaxylenes (OPXs) with a view to providing a molecular tool box for the construction of nano architectures-such as spheres, cages, capsules, metal-organic frameworks (MOFs), metal-organic polyhedrons (MOPs) and covalent-organic frameworks (COFs), to name but a few-of well-defined sizes and shapes. Twisting between the planes of contiguous paraxylene rings is generated by the steric hindrance associated with the methyl groups and leads to the existence of soluble molecular gauge blocks without the need, at least in the case of the lower homologues, to introduce long aliphatic side chains onto the phenylene rings in the molecules. Although soluble molecular gauge blocks with up to seven consecutive benzenoid rings have been prepared employing repeating paraxylene units, in the case of the higher homologues it becomes necessary to introduce hexyl groups instead of methyl groups onto selected phenylene rings to maintain solubility. A hexyl-doped compound with seven substituted phenylene rings was found to be an organogelator, exhibiting thermally reversible gelation and a critical gelation concentration of 10 mM in dimethyl sulfoxide. Furthermore, control over the morphology of a series of hexyl-doped OPXs to give microfibers, microaggregates, or nanofibers, was observed as a function of their lengths according to images obtained by scanning electron microscopy. The modular syntheses of the paraphenylene derivatives rely heavily on Suzuki-Miyaura cross-coupling reactions. The lack of π-π conjugation in these derivatives that is responsible for their enhanced solubilities was corroborated by UV/Vis and fluorescent spectroscopy. In one particular series of model OPXs, dynamic (1)H NMR spectroscopy was used to probe the stereochemical consequences of having from one up to five axes of chirality present in the same molecule. The Losanitsch sequence for the compounds with 1-3 chiral axes was established, and a contemporary mathematical way was found to describe the sequence. The development of the ways and means to make molecular gauge building blocks will have positive repercussions on the control of nanostructures in general. Their incorporation into extended structures with the MOF-74 topology provides an excellent demonstration of the potential usefulness of these molecular gauge blocks.

Bacterial cellulose: A promising biopolymer with interesting properties and applications.

The ever-increasing demands for materials with desirable properties led to the development of materials that impose unfavorable influences on the environment and the ecosystem. Developing a low-cost, durable, and eco-friendly functional material with biological origins has become necessary to avoid these consequences. Bacterial cellulose generated by bacteria dispenses excellent structural and functional properties and satisfies these requirements. BC and BC-derived materials are essential in developing pure and environmentally safe functional materials. This review offers a detailed understanding of the biosynthesis of BC, properties, various functionalization methods, and applicability in biomedical, water treatment, food storage, energy conversion, and energy storage applications.

Ion storage performance of a polymer for mono-, di- and tri-valent metal ions in non-aqueous electrolytes.

A cost-effective quinone-pyrrole conjugated polymer is utilized as an electrode for non-aqueous Al, Zn and Li-ion batteries. Reversible capacities of 120 mA h g-1 at 50 mA g-1 for Al-ion batteries and 108 and 175 mA h g-1 for Zn and Li-ion batteries, respectively, at 100 mA g-1 are observed. Thousands of stable cycles were obtained at 1000 mA g-1 current density, providing sufficient evidence for a range of applications of the polymer in electrochemical energy storage.

Off-Planar, Two-Dimensional Polymer Cathode for High-Rate, Durable Rechargeable Magnesium Batteries.

Rechargeable magnesium batteries are of considerable interest due to their high theoretical capacity, and they are projected as good alternates for stationary energy storage and electric vehicles. Sluggish Mg2+ kinetics and scarce availability of suitable cathode materials are major issues hindering the progress of rechargeable magnesium batteries. Herein, a conjugated, off-planar, two-dimensional (2D) polymer is explored for reversible magnesium storage. The polymer cathode reveals high capacity and high cycling stability with high rate capability. Replacing the Mg metal anode with the Mg alloy, AZ31 further enhances the ion storage performance. At a high current density of 2 A g-1, stable capacity is shown for almost 5000 cycles with 99% Coulombic efficiency. A composite of carbon nanotube with the polymer delivers capacity values higher (>1.5 times) than that of a pristine polymer at a current density of 2 A g-1 and shows cycling up to 5 A g-1. Electrokinetic studies reveal a contribution of pseudocapacitive nature, and the mechanism is investigated by ex situ X-ray photoelectron spectroscopy and infrared spectroscopy. The use of 2D polymer electrodes opens up opportunities for developing high-rate, high-capacity, and stable rechargeable magnesium ion batteries.

Copper (0) Mediated Single Electron Transfer-Living Radical Polymerization of Methyl Methacrylate: Functionalized Graphene as a Convenient Tool for Radical Initiator.

Polymer nanocomposites have been synthesized by the covalent addition of bromide-functionalized graphene (Graphene-Br) through the single electron transfer-living radical polymerization technique (SET-LRP). Graphite functionalized with bromide for the first time via an efficient route using mild reagents has been designed to develop a graphene based radical initiator. The efficiency of sacrificial initiator (ethyl α-bromoisobutyrate) has also been compared with a graphene based initiator towards monitoring their Cu(0) mediated controlled molecular weight and morphological structures through mass spectroscopy (MOLDI-TOF) and field emission scanning electron microscopy (FE-SEM) analysis, respectively. The enhancement in thermal stability is observed for graphene-grafted-poly(methyl methacrylate) (G-g-PMMA) at 392 °C, which may be due to the influence ofthe covalent addition of graphene, whereas the sacrificial initiator used to synthesize G-graft-PMMA (S) has low thermal stability as analyzed by TGA. A significant difference is noticed on their glass transition and melting temperatures by DSC. The controlled formation and structural features of the polymer-functionalized-graphene is characterized by Raman, FT-IR, UV-Vis spectroscopy, NMR, and zeta potential measurements. The wettability measurements of the novel G-graft-PMMA on leather surface were found to be better in hydrophobic nature with a water contact angle of 109 ± 1°.

High performance platinized titanium nitride catalyst for methanol oxidation.

Platinized TiN is shown to be a very good catalyst for the electrochemical oxidation of methanol; it does not contain Ru and the CO poisoning effect is alleviated by the presence of TiN.

Is Reactive Dengue NS1Antigen Test a Warning Call for Hospital Admissions?

INTRODUCTION: Dengue fever is a major public health problem worldwide. The 2011 revised World Health Organization (WHO) guidelines have emphasized on early diagnosis and intervention to reduce the case fatality rate due to dengue fever. Rapid diagnostic tests like NS1 antigen assays have improved the detection of cases in early clinical phase of illness but its role as a predictor of severe dengue infection is not very clear. AIM: To evaluate the utility of NS1 Ag assay as an early diagnostic marker and predictor of severe dengue infection. MATERIALS AND METHODS: All children (0-12 years of age) diagnosed and confirmed with dengue fever at a tertiary care hospital in Puducherry between 01(st) August 2012 and 31(st) July 2015 were reviewed retrospectively from hospital case records as per the revised WHO guidelines for dengue fever. The diagnosis was confirmed by NS1antigen-based ELISA test or dengue serology for IgM and IgG antibodies and the data were analysed using SPSS 16.0 statistical software. After collecting all the data, all the variables were summarised by descriptive statistics. Categorical variables were expressed as frequencies and percentages, and then analysed by the χ(2) test or fishers exact test, where appropriate. Significance was taken at p-value< 0.05. RESULTS: Among the 261 confirmed cases of dengue fever non-severe dengue and severe dengue infection was seen in 60.9% and 39.1% respectively. The mean age of presentation was 6.9 years and M:F ratio was 1.2:1. NS1 Ag was positive in 217 cases (83.1%) and among them non-severe dengue and severe dengue was seen in 65.9% and 34.1% cases respectively. A total of 44 cases (16.9%) were negative for NS1 Ag assay and positive for IgM MAC ELISA and among them 16 children (36.4%) had non-severe dengue infection where as 28 children (63.6%) had severe dengue infection. Secondary infection with (MAC-ELISA IgG) was seen in 17 cases (6.5%). NS1Ag assay was predominantly positive in acute phase sera, where as IgM/IgG MAC ELISA was predominantly positive in convalescent phase sera. There were six deaths (2.3%) and the common causes of poor outcome were multiorgan failure, encephalopathy and refractory shock. CONCLUSION: NS1 Ag assay is a useful early diagnostic marker for dengue fever but cannot be used as an early predictor of severe dengue infection. The criteria for admission in hospitals of cases of dengue fever should be based on clinical warning signs rather than positive NS1 Antigen test.

Clinically Profiling Pediatric Patients with Dengue.

OBJECTIVE: To study the clinical profile and outcome of dengue fever in children at a tertiary care hospital in Puducherry. MATERIALS AND METHODS: All children (0-12 years of age) diagnosed and confirmed as dengue fever from August 2012 to January 2015 were reviewed retrospectively from hospital case records as per the revised World Health Organization guidelines for dengue fever. The diagnosis was confirmed by NS1 antigen-based ELISA test or dengue serology for IgM and IgG antibodies, and the data were analyzed using SPSS 16.0 statistical software. After collecting the data, all the variables were summarized by descriptive statistics. RESULTS: Among the 261 confirmed cases of dengue fever non-severe and severe dengue infection was seen in 60.9% and 39.1%, respectively. The mean age (standard deviation) of the presentation was 6.9 + 3.3 years and male: female ratio was 1.2:1. The most common clinical manifestations were fever (94.6%), conjunctival congestion (89.6%), myalgia (81.9%), coryza (79.7%), headache (75.1%), palmar erythema (62.8%), and retro-orbital pain (51.3%). The common early warning signs at the time of admission were persistent vomiting (75.1%), liver enlargement (59.8%), cold and clammy extremities (45.2%), pain abdomen (31.0%), hypotension (29.5%), restlessness (26.4%), giddiness (23.0%), bleeding (19.9%), and oliguria (18.4%). The common manifestation of severe dengue infection was shock (39.1%), bleeding (19.9%), and multi-organ dysfunction (2.3%). The most common complications were liver dysfunction, acute respiratory distress syndrome, encephalopathy, pleural effusion, ascites, myocarditis, myositis, acute kidney injury, and disseminated intravascular coagulopathy. Platelet count did not always correlate well with the severity of bleeding. There were six deaths (2.3%) and out of them four presented with impaired consciousness (66.6%). The common causes for poor outcome were multiorgan failure, encephalopathy, and fluid refractory shock. CONCLUSION: There has been a resurgence of dengue fever with a change in the pattern of presentation during the recent epidemics. Clinical vigilance and awareness regarding the changing epidemic pattern and timely detection of cases are vital to reduce mortality and morbidity due to severe dengue infection.

Case studies on the formation of chalcogenide self-assembled monolayers on surfaces and dissociative processes.

This report examines the assembly of chalcogenide organic molecules on various surfaces, focusing on cases when chemisorption is accompanied by carbon-chalcogen atom-bond scission. In the case of alkane and benzyl chalcogenides, this induces formation of a chalcogenized interface layer. This process can occur during the initial stages of adsorption and then, after passivation of the surface, molecular adsorption can proceed. The characteristics of the chalcogenized interface layer can be significantly different from the metal layer and can affect various properties such as electron conduction. For chalcogenophenes, the carbon-chalcogen atom-bond breaking can lead to opening of the ring and adsorption of an alkene chalcogenide. Such a disruption of the π-electron system affects charge transport along the chains. Awareness about these effects is of importance from the point of view of molecular electronics. We discuss some recent studies based on X-ray photoelectron spectroscopy that shed light on these aspects for a series of such organic molecules.

Porphyrinic supramolecular daisy chains incorporating pillar[5]arene-viologen host-guest interactions.

A porphyrin functionalised with pillar[5]arene and a viologen at its 5- and 15-meso positions assembles in a head-to-tail manner, producing linear supramolecular daisy chains in dichloromethane. At high concentrations, it forms an organogel which has been investigated by electron microscopy and rheological measurements, paving the way for the preparation of other functional supramolecular assemblies which harness viologen⊂pillararene host-guest interactions.

Orientation dependent electrocatalysis using self-assembled molecular films.

Surface orientation of self-assembled molecular films of 2,9,6,23-tetraamino cobalt phthalocyanine on gold and silver is shown to determine the nature and the products of the electrocatalytic reduction of oxygen.