Excited Charge Separation in a π-Interacting Phenothiazine-Zinc Porphyrin-Fullerene Donor-Acceptor Conjugate.

We have designed, synthesized, and characterized a donor-acceptor triad, SPS-PPY-C60, that consists of a π-interacting phenothiazine-linked porphyrin as a donor and sensitizer and fullerene as an acceptor to seek charge separation upon photoexcitation. The optical absorption spectrum revealed red-shifted Soret and Q-bands of porphyrin due to charge transfer-type interactions involving the two ethynyl bridges carrying electron-rich and electron-poor substituents. The redox properties suggested that the phenothiazine-porphyrin part of the molecule is easier to oxidize and the fullerene part is easier to reduce. DFT calculations supported the redox properties wherein the electron density of the highest molecular orbital (HOMO) was distributed over the donor phenothiazine-porphyrin entity while the lowest unoccupied molecular orbital (LUMO) was distributed over the fullerene acceptor. TD-DFT studies suggested the involvement of both the S2 and S1 states in the charge transfer process. The steady-state emission spectrum, when excited either at porphyrin Soret or visible band absorption maxima, revealed quenched emission both in nonpolar and polar solvents, suggesting the occurrence of excited state events. Finally, femtosecond transient absorption spectral studies were performed to witness the charge separation by utilizing solvents of different polarities. The transient data was further analyzed by GloTarAn by fitting the data with appropriate models to describe photochemical events. From this, the average lifetime of the charge-separated state calculated was found to be 169 ps in benzonitrile, 319 ps in dichlorobenzene, 1.7 ns in toluene for Soret band excitation, and ∼320 ps for Q-band excitation in benzonitrile.

Molecularly Engineered Multifunctional Bridging Layer Derived from Dithiafulavene Capped Spiroxanthene for Stable and Efficient Perovskite Solar Cells.

This study introduces a novel approach centered around the design and synthesis of an interfacial passivating layer in perovskite solar cells (PSCs). This architectural innovation is realized through the development of a specialized material, termed dithiafulvene end-capped Spiro[fluorene-9,9'-xanthene], denoted by the acronym AF32. In this design architecture, dithiafulvene is thoughtfully attached to the spiroxanthene fluorene core with phenothiazine as the spacer unit, possessing multiple alkyl chains. AF32 passivates interfacial defects by coordinating the sulfur constituents of the phenothiazine and dithiafulvene frameworks to the uncoordinated Pb2+ cations on the surface of the perovskite film, and the alkyl chains construct a hydrophobic environment, preventing moisture from entering the hydrophilic perovskite layer and improving the long-term stability of PSCs. Furthermore, this conductive interlayer facilitates hole transport in PSCs due to its well-aligned molecular orbital levels. Such improvements translated into an enhanced power conversion efficiency (PCE) of 22.6% for the device employing 1.5 mg/mL AF32, and it maintained 85% of its initial PCE after more than 1800 h under ambient conditions [illumination and 45 ± 5% relative humidity (RH)]. This study not only marks progress in photovoltaic technology but also expands our understanding of manipulating interfacial properties for optimized device performance and stability.

BODIPY-Based Mitochondrial Targeted NIR-Responsive CO-Releasing Platform for the On-Demand Release of CO to Treat Cancer.

It is an established fact that cancer is one of the most serious public health issues after coronary artery disease. Thus, exploring more effective and efficient therapeutic protocols over the traditional chemotherapeutic strategy is imperative to improving cancer survivorship and patient quality of life. In this respect, recent reports on molecularly engineered meso-substituted BODIPY have shown remarkable effects as a photoresponsive CO-releasing platform for the on-demand release of CO to treat cancer. Herein, we designed and synthesized two meso-substituted BODIPY photoresponsive CO-releasing molecules (photoCORMs). These BODIPY derivatives were tethered to a phenoxymethylpyridine moiety and oligoethylene glycol to maintain a hydrophilic-hydrophobic balance and improved cell permeability. The cell imaging experiments demonstrated that oligoethylene glycol containing photoCORM-1 efficiently internalized and preferentially localized at the mitochondria. To understand the mechanistic aspect of preferential localization into the mitochondria, live cell imaging was also carried out. Photorelease of CO was directly monitored by the inline IR spectroscopic technique. Finally, in vitro cytotoxicity and apoptosis assays on MDA-MB-231 cell lines clearly showed that photoCORM-1 induced apoptosis-mediated cell killing on account of photoreleased CO, which otherwise showed insignificant toxicity even at a very high concentration of ∼50 µM.

Photocatalyst-free visible-light triggered amination of benzo[c][1,2,5]thiadiazole: direct C-N bond formation from C(sp2)-H bond.

The photoredox amination of arene protocols mostly comprises photocatalyst-mediated transformations. Herein, we presented the photocatalyst-free, visible-light promoted, direct conversion of C(sp2)-H to C(sp2)-N method. Multipurpose benzothiadiazoles are used as model synthons and secondary amines as aminating agents. Mechanistic study reveals that the radical reaction mechanism proceeds through nitrogen-centered radical generation, followed by the addition of arenes, which was demonstrated for the present amination protocol of benzothiadiazole with secondary amines in an atom economical fashion.

Phenothiazine functionalized fulleropyrrolidines: synthesis, charge transport and applications to organic solar cells.

A series of phenothiazine-C60/70 dyads containing fulleropyrrolidine tethered to C-3 position (C60-PTZ and C70-PTZ) or to the heteroatom N-position via either phenyl (C60-Ph-PTZ and C70-Ph-PTZ) or phenoxyethyl linkers (C60-PhOEt-PTZ and C70-PhOEt-PTZ) of the phenothiazine were synthesized and light-induced electron transfer events were explored. Optimized studies suggested that the highest molecular orbital (HOMO) resides on donor phenothiazine moiety while lowest molecular orbital (LUMO) on the acceptor fulleropyrrolidine moiety of the dyads. Optical and electrochemical properties suggested no electronic communication between the donor and acceptor moieties in the ground state. However, steady-state emission studies in solvents of varied polarity, involving selective excitation of C60/C70, disclosed that the emission intensity of C60/C70 was quenched in the dyads in the increasing order, C60/70-PTZ > C60/70-Ph-PTZ > C60/70-PhOEt-PTZ as a consequence of the donor-acceptor distance resulted due to spacer lengths. Also, the emission quenching is more pronounced in polar solvents such as DMF compared to a non-polar solvent, toluene. With the support of parallel electrochemical studies, the emission quenching is attributed to intramolecular photo-induced electron transfer occurring from PTZ to (C60/C70)* generating a radical ion pair, PTZ+⋅-C60-⋅/PTZ+⋅-C70-⋅. Finally, bulk heterojunction (BHJ) solar cells devices inverted fashion prepared by employing the dyads as acceptors, and PTB7 as donor, suggested that the devices prepared from C70 derivatives i.e., PTB7:C70-PTZ and PTB7:C70-PhOEt-PTZ exhibited better power conversion efficiency of 2.66% and 2.15%, respectively over C60 derivatives i.e., PTB7:C60-PTZ and PTB7:C60-PhOEt-PTZ with the efficiencies of 1.80 and 1.72%, respectively. AFM studies revealed that the poor performance of PTB7:C60-PTZ- and PTB7:C60-PhOEt-PTZ-based devices can be ascribed to the lower solubility of the dyads in 1,2-DCB solvent leading to rough morphology.

Two phase algorithm for bi-objective relief distribution location problem.

The location planning of relief distribution centres (DCs) is crucial in humanitarian logistics as it directly influences the disaster response and service to the affected victims. In light of the critical role of facility location in humanitarian logistics planning, the study proposes a two-stage relief distribution location problem. The first stage of the model determines the minimum number of relief DCs, and the second stage find the optimal location of these DCs to minimize the total cost. To address a more realistic situation, restrictions are imposed on the coverage area and capacity of each DCs. In addition, for optimally solving this complex NP-hard problem, a novel two-phase algorithm with exploration and exploitation phase is developed in the paper. The first phase of the algorithm i.e., exploration phase identifies a near-optimal solution while the second phase i.e. exploitation phase enhances the solution quality through a close circular proximity investigation. Furthermore, the comparative analysis of the proposed algorithm with other well-known algorithms such as genetic algorithm, pattern search, fmincon, multistart and hybrid heuristics is also reported and computationally tested from small to large data sets. The results reveal that the proposed two-phase algorithm is more efficient and effective when compared to the conventional metaheuristic methods.

[1]Benzothieno[3,2-b][1]benzothiophene-based dyes: effect of the ancillary moiety on mechanochromism and aggregation-induced emission.

It is an established fact that [1]benzothieno[3,2-b][1]benzothiophene (BTBT) is a champion molecule for high-mobility OFET devices. Recently, it has also been utilized in dye-sensitized solar cells (DSSCs) and organic photovoltaics (OPVs) as an alternative to fullerene (non-fullerene acceptor). Considering the advantageous features of BTBT, we herein report its aggregation-induced emission (AIE) and mechanofluorochromic (MFC) behaviour for the first time. We have designed and synthesized two new BTBT derivatives: [1]benzothieno[3,2-b][1]benzothiophene-tetraphenylethylene (BTBT-TPE) and [1]benzothieno[3,2-b][1]benzothiophene-phenyl-N,N-dimethylamine (BTBT-NMe). The donor-π-acceptor-π-donor-integrated BTBT-TPE showed AIE whereas BTBT-NMe showed aggregation-caused quenching (ACQ), as evident by their quantum yield and lifetime results. BTBT-NMe was found to possess great interaction, resulting in the halochromic (protonation) effect. The theoretical calculation of the electronic distribution and energy investigation were consistent with the experimental outcomes. The electron contribution of the HOMO is high for BTBT-NMe at the donor, which can be attributed to the weaker donating nature of TPE compared to that of the NMe group. Overall, the results indicate the potential of the mechanical stimuli and aggregation response of the studied compounds for further investigation.

Enhanced permeability and retention effect: A key facilitator for solid tumor targeting by nanoparticles.

Exploring the enhanced permeability and retention (EPR) effect through therapeutic nanoparticles has been a subject of considerable interest in tumor biology. This passive targeting based phenomenon exploits the leaky blood vasculature and the defective lymphatic drainage system of the heterogeneous tumor microenvironment resulting in enhanced preferential accumulation of the nanoparticles within the tumor tissues. This article reviews the fundamental studies to assess how the EPR effect plays an essential role in passive targeting. Further, it summarizes various therapeutic modalities of nanoformulation including chemo-photodynamic therapy, intravascular drug release, and photothermal immunotherapy to combat cancer using enhanced EPR effect in neoplasia region.

Efficient Medium Bandgap Electron Acceptor Based on Diketopyrrolopyrrole and Furan for Efficient Ternary Organic Solar Cells.

We report the design of novel medium bandgap nonfullerene small molecule acceptor NFSMA SPS-TDPP-2CNRh with A2-π-A1-π-A2 architecture, with the molecular engineering of this material comprising a strong electron-accepting backbone unit DPP (A1) as the acceptor, which is attached to the dicyanomethylene-3-hexylrhodanine (A2) acceptor via a furan (π-spacer) linker. We systematically studied its structural and optoelectronic properties. The incorporation of dicyanomethylene-3-hexylrhodanine and furan enhance the light absorption and electrochemical properties by extending π-conjugation and is anticipated to improve VOC by decreasing the LUMO level. The long alkyl chain units were responsible for the better solubility and aggregation of the resultant molecule. Binary BHJ-OSCs constructed with polymer P as the donor and SPS-TDPP-2CNRh as the acceptor resulted in a PCE of 11.49% with improved VOC = 0.98 V, JSC = 18.32 mA/cm2, and FF = 0.64 for P:SPS-TDPP-2CNRh organic solar cells. A ternary solar cell device was also made using Y18-DMO and SPS-TDPP-2CNRh as acceptors having complementary absorption profiles and polymer P as the donor, resulting in a PCE of 15.50% with improved JSC = 23.08 mA/cm2, FF = 0.73, and VOC = 0.92 V for the P:SPS-TDPP-2CNRh:Y18-DMO solar cell. The ternary OSCs with SPS-TDPP-2CNRh as the host acceptor in the P:Y18-DMO binary film were shown to have improved PCE values, which is mainly attributed to the effective photoinduced charge transfer through multiple networks and the use of excitons from SPS-TDPP-2CNRh and Y18-DMO. Moreover, in the ternary BHJ active layers, the superior stable charge transport that was observed compared to the binary counterparts may also lead to an increase in the fill factor. These results demonstrate that combining medium bandgap and narrow bandgap NFSMAs with a wide bandgap polymer donor is a successful route to increasing the overall PCE of the OSCs via the ternary BHJ concept.

Designing dynamic reverse logistics network for post-sale service.

The paper addresses the problem of designing a multi-country production-distribution network that also provides services such as repairs and remanufacturing. The proposed work concentrates primarily on post-sale service provided by the firm under warranty returns. The proposed model assumes that existing warehouses can also serve as collection centres or repair centres for reverse logistics. In addition, the model also explores the possibility of establishing a new facility. Hybrid facilities are considered because of their huge cost-cutting potential due to equipment sharing and space sharing. The capacity of hybrid facilities can be expanded to a predefined limit to process returned products without hampering forward logistics operations. However, if a product cannot be repaired at the warehouse, it is transported to the plant for remanufacturing. The model optimizes the overall configuration and operation cost of the production-distribution network. The production-distribution model developed in the paper is a mixed-integer nonlinear program (MINLP) that is later transformed to a mixed-integer linear program to reduce the solution time. The usefulness of the model is illustrated using a randomly generated dataset. The model identifies (a) the optimal locations/allocations of the existing/new facilities, (b) the distribution of returned products for refurbishing and remanufacturing, and (c) the capacity expansion of the existing plants and warehouses to facilitate remanufacturing and repair services.

Multi-echelon agri-food supply chain network design integrating operational and strategic objectives: a case of public distribution system in India.

The global concern to ensure the availability of food for the growing world's population draws urgent attention towards the inefficiencies in agri-food supply chains. Agri-food supply chains are inherently complex to manage than other supply chains mainly because of their multi-echelon structure, deteriorating product quality with time and changes in storage conditions which leads to significant amount of food loss and wastage. Additionally, any natural or man-made disaster further disrupts the chain and leads to high food loss, high supply chain costs, reduced food availability and poor food quality. Hence, there is a need to design resilient and efficient agri-food supply chain network for optimal multi-echelon storage and distribution to reduce food loss and quality degradation. For this purpose, a Fuzzy Multi Objective Linear Program (FMOLP) is proposed in this paper for integrated food procurement, storage and distribution under cost, resilience and quality considerations. The proposed model integrates the short-term operational objective of cost optimization with the long-term sustainable objectives of food loss minimization and resilience maximization. The proposed FMOLP is illustrated using a realistic case of Public Distribution System using the data benchmarked with the numbers reported by the Food corporation of India. The detailed computational analysis carried out in the paper in investigates three categories of problem sizes to compare and contrast the decisions using different strategies and to provide organizational, operational and policy insights on the trade-off between cost, food loss and resilience.

Selection of healthcare waste disposal firms using a multi-method approach.

The aim of this study is to propose a hybrid multi criteria decision making model with a linear programming (LP) model to tackle the issue of safe disposal of hazardous and infectious healthcare waste. For this, ten criteria in this study have been identified from literature and field surveys which are modelled using Decision making trial and evaluation (DEMATEL) and Analytic network process (ANP) methods to select the best disposal firm i.e. single sourcing for a hospital. We found that Experience of the firm, Technology for disposal, and Waste collection infrastructure acts as the most vital criteria in selecting a healthcare waste disposal firm for single sourcing. Furthermore, to optimize the total value of disposal and mitigating the risk involved in disposing waste through single sourcing; the LP model considering constraints such as waste lose constraint and waste processing constraint etc. Is solved for multiple sourcing using Lingo 18.0. The solution to LP results into allocation of 500, 500, and 1000 (kg/day) disposables to healthcare waste disposal firms D1, D2 and D3, respectively. The multi-method approach proposed in this study helps the hospital management in selecting economically, socially, and environmentally sustainable healthcare waste disposal firm.

Lead-halides Perovskite Visible Light Photoredox Catalysts for Organic Synthesis.

Lead-halide perovskites has grabbed great attention in recent years due to its unique photophysical and electrical properties. It has open new window in organic solar cell application for commercial point. Research has extended its application further towards visible light photoredox catalysts for organic synthesis. Due to intrinsic redox properties, sharp absorption and emissions patterns makes lead-halide perovskites as promising photoredox catalyst. In the presence of light, perovskite absorbs light, generates electrons/holes, which can reduce or oxidize species at reactive centres of organic molecule, leads to organic transformation. Lead-halide perovskites are used as heterogeneous catalysts for small molecules activations like CO, CH4 and NO, also suitable photocatalysts for organic bond formations, oxidations, reductions, polymerizations and dimerization transformations. Recent literatures have set another milestone for perovskite materials in organic synthesis. This review provides information on lead-halides perovskite in visible-light photoredox catalysis such as C-C, C-X (X-halo, hetero atom) bond formations C-H arylation.

Lead-Free, Water-Stable A3 Bi2 I9 Perovskites: Crystal Growth and Blue-Emitting Quantum Dots [A=CH3 NH3 + , Cs+ , and (Rb0.05 Cs2.95 )+ ].

Despite the great success in the increase in the power conversion efficiency of lead halide perovskite solar cells, the toxicity of lead and the unstable nature of the materials are still major concerns for their wider implementation at the industrial level. Herein, large-size single crystals (SCs) are developed in HI solution by using a temperature lowering method and nanocrystals (NCs) of A3 Bi2 I9 perovskites [where A=CH3 NH3 + (MA)+ , Cs+ , and (Rb0.05 Cs2.95 )+ ] are formed in ethanol (EtOH) and toluene (TOL). The stability of A3 Bi2 I9 perovskite is investigated by immersing the SCs for 24 h and pellets for 12 h in water. Moreover, the A3 Bi2 I9 perovskite NCs displays a promising photoluminescence quantum yield of 17.63 % and a long lifetime of 8.20 ns.

Spoof surface plasmonic transmission line with high isolation and low propagation loss.

A novel compact spoof surface plasmonic (SSP) transmission line (TL) consisting of a stem-shaped periodic structure is proposed to achieve high field confinement in the higher frequency range (microwave to terahertz). The dispersion characteristic of the proposed stem-shaped SSP unit cell exhibits much lower asymptotic frequency and higher field confinement than the conventional coplanar waveguide (CPW) and the rectangular SSP unit cell structure without increasing the overall transverse dimension, i.e., improved signal propagation performance with reduced cross-sectional area. The numerical study of the multi-conductor line based on the proposed stem-shaped SSP unit cell shows that it has improved propagation and isolation features in comparison to the conventional TL structures. Here, the improved isolation is characterized in terms of the mutual coupling (MC) between the two adjacent lines designed using the stem-shaped SSP unit cell, which is not found to significantly increase with an increase in the coupling length unlikely in the conventional TLs. For the proposed SSP-based multi-conductor line, the MCs for 1.6, 2.25, and 4.15λ coupling lengths with fixed separation of 0.175λ are found to be 22, -19.8, and -17.55dB, respectively.

Phenothiazine-Based Hole Transport Materials for Perovskite Solar Cells.

The promising photovoltaic solar cells based on the perovskite light-harvesting materials have attracted researchers with their outstanding power conversion efficiencies (over 23% certified). The perovskite work has geared up in just under a decade and is competing with well-established semiconductor technologies such as silicon (Si), copper indium gallium selenide (CIGS), and cadmium telluride (CdTe). To commercialize the perovskite solar cells, their stability is the major concern. To address the stability issue, several factors need to be taken into account, and one of them is developing stable hole transport materials (HTMs), which are the essential building blocks. In this mini-review, we will discuss the important features of the HTMs, such as design and development of phenothiazine-based HTMs. Since phenothiazine is a low cost and stable molecule compared to the spiro-OMeTAD, it can be modified further via molecular engineering.

Near-Infrared (>1000†nm) Light-Harvesters: Design, Synthesis and Applications.

Organic molecules can absorb or emit light in UV, visible and infra-red (IR) region of solar radiation. Fifty percent of energy of solar radiation lies in the IR region of solar spectrum and extended π-conjugated molecules containing low optical band gap can absorb NIR radiations. Recently IR molecules have grabbed the attention of synthetic chemists. Although only few molecules have been reported so far such as derivative of BODIPY, naphthalimide, porphyrins, perylene, BBT etc., they have shown highest absorbing capacity towards greater than 1100 nm. These compounds have potential applications in different fields, such as for biomedical and optoelectronic applications. In this review, we present different classes of light-harvesters with harvesting range above 1000 nm.

Distribution network model using big data in an international environment.

This paper proposes dynamic mixed integer facility location model to design an international manufacturing network (IMN). The proposed model considers a broad facility network linking production and distribution facilities located internationally. The proposed model discussed in the paper assumes significance over the traditional manufacturing model as it provides a country specific analysis making it more convenient for the decision maker to devise country specific strategies within an international ecosystem. Therefore, the model considers import export cost, loan subsidies along with depreciation expense and other operating costs applicable to specific country. The objective of the model is to identify optimal facility locations and the production distribution in the entire network to meet the demand of global markets. The proposed model is illustrated and computationally tested using two cases. Model parameters are mapped using 3Vs of Big Data viz. Volume, Velocity and Variety.

Ni-Doped CsPbBr3 Perovskite: Synthesis of Highly Stable Nanocubes.

A nanocube of Ni-doped CsPbBr3nanocrystals (NCs) has been successfully synthesized and characterized by various spectroscopy techniques such as High-resolution transmission electron microscopy (HR-TEM), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), etc. The optoelectronic properties of NCs have been investigated with different solvents. HR-TEM and FE-SEM reveal that the obtained Ni-doped CsPbBr3NCs exhibit cubic-rectangular morphologies with different sizes. Furthermore, the radiative exciton kinetics of NCs was examined using the time-correlated single photon counting (TCSPC) technique. The present study ravels that synthesized nanocubes are highly stable.

Butterfly architecture of NIR Aza-BODIPY small molecules decorated with phenothiazine or phenoxazine.

This is the first report on the highest efficiency NIR absorbing Aza-Bodipy small molecules. The molecular engineering of newly synthesized NIR absorbing Aza-Bodipy dyes consists of covalently linked phenothiazine (AZA-PTZ-BOD) and phenoxazine (AZA-POZ-BOD) moieties as terminal groups and Aza-Bodipy as a central core moiety. The highest efficiency for OPV devices of 8.23% is achieved for AZA-PTZ-BOD.