Wahab K. A. Al-Ithawi

Lawsone and its derivatives have a variety of applications in the field of pharmaceutical research: as drug candidates, reagents for the chelation and recognition of metal cations (including those for catalytic applications), chemosensors for anions, and materials for energy storage applications. Moreover, there are some reports on the application of lawsone and its derivatives in the forensic science field. One of the most attractive features of lawsones is their bright color and well-pronounced fluorescence, which can be altered due to covalent or non-covalent interactions with various species. In this work, we endeavor to present our recent findings on the fluorescence response of lawsone and its methyl ester to nitro compounds and explosives components, such as 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenole (picric acid, PA), 2-nitromesitylene (2-NM), 4-nitrophenol (NP) as well as Fe3+ (FeCl3). In all the cases a dramatic fluorescence turn-off response was observed with up to 104 M-1 quenching constants. To explore the practical application of lawsone derivatives a mechanochemical modification of polyvinyl chloride (PVC) with lawsone residues was carried out, and thus obtained polymer was found to exhibit a pronounced fluorescence turn-off response to the both nitro-compounds and Fe3+ with as high as 104 M–1 quenching constants.

The current study aims to address the environmental challenge of nutrient enrichment in freshwater ecosystems, particularly in the Tigris River, by providing a comprehensive assessment of nutrient concentrations, including sulfates (SO₄²⁻), nitrites (NO₂⁻), nitrates (NO₃⁻), ammonium (NH₄⁺), and phosphates (PO₄³⁻), evaluating the temporal and spatial distribution, and identifying the most important human -based activities contributing to the load of nutrient. Samples were collected from six sites distributed along the river within Baghdad city, over a three-year period (2020–2022). The results showed a clear spatial variation, with concentrations of most nutrients gradually rising towards southern sites, indicating the impact of accumulated human activities such as sewage, industrial discharges, and agricultural runoff. Nitrates and phosphates were highest at sites near dense urban and industrial areas, while nitrite concentrations were generally low but appeared to be an indicator of incomplete biological activity. Sulfate concentrations (211–233 mg/L) exceed the environmental limits allowed under the 1967 Iraqi River Maintenance Regulation, and show a need for better water management and regular monitoring. In terms of time, the data showed significant annual changes in nutrient concentrations, with an increase in sulfate and phosphate concentrations recorded in 2022 and 2021, respectively, compared to previous years, which may reflect an increase in untreated discharges or the effects of drought and reduced river flow. In contrast, nitrate concentrations declined sharply in 2021 and rose again in 2022. Nitrite and ammonia concentrations remained relatively stable over the three years. The research recommends the need to strengthen continuous environmental monitoring systems, update national laws to include nutrient pollutants such as nitrite, and enhance the efficiency of water treatment plants, with the aim of reducing eutrophication and protecting the river ecosystem.

Equol (4',7-isoflavandiol) is a metabolite of isoflavandiol estrogen daidzein, which is found in soybeans and other plant sources. In this manuscript we wish to report the first mechanochemical approach to equol-based polymers, such as polycarbonate and polyester. Our approach involves the polycondensation reaction between 4',7-isoflavandiol (rac-equol) and triphosgene or oxalyl chloride under ball-milling conditions. The obtained polymers were characterized by means of 1H NMR- and IR-spectroscopy. To explore the possibility of practical application of the abovementioned polymers, the fluorescence “turn-off” response of the equol-based polycarbonate towards some common nitroanalytes (2,4-dinitrotioluene (DNT) and 2,4,6-trinitrophenol (picric acid, PA)) was investigated, and up to 1o5 M–1 Stern-Volmer constants were observed.

Iptycenes are common building blocks for the small-molecules or polymer-based chemosensors and fluorophores. In addition, iptycene derivatives are widely presented in polymers of intrinsic microporosity (PIMs) as materials for the separation and purification technologies. In this manuscript we wish to report a mechanochemical approach to pentiptycene-based polyesters and polycarbonates as, possibly, new representatives of PIMs. Our approach involves the polycondensation reaction between 5,7,12,14-tetrahydro-5,14:7,12-bis([1,2]benzeno)pentacene-6,13-diol (pentiptycene-6,13-diol) and triphosgene or oxalyl chloride under ball-milling conditions. The obtained polymers were characterized by means of 1H NMR- and IR-spectroscopy. As the last step, the fluorescence “turn-off” response of pentiptycene-6,13-diol and two pentiptycene-based polymers towards nitroanalytes (2,4-dinitrotioluene (DNT) and 2,4,6-trinitrophenole (picric acid, PA)) was investigated, and Stern-Volmer constants as high as 1o4 M–1 were observed.

Polyvinyl chloride (PVC) plays an important role in industry; however, due to its uncontrolled accumulation in the environment, the methods for its utilization are of high demand. Herein we wish to report an approach for the utilization of PVC via its use as a carrier for some azole-based drugs, such as 2-mercaptobenzothiazole (multi-activity drug), 4-oxo-1,4-dihydropyrazolo[5,1-c]-1,2,4-triazine-3,8-dicarboxylic acid diethyl ester (antidiabetic drug) and 5-methyl-6-nitro-7-oxo-1,2,4-triazolo[1,5-a]pyrimidinide (antiviral drug). The abovementioned approach involves the reaction between PVC and potassium or sodium salts of these azole-based drugs either in solution or under ball-milling conditions. The as-obtained PVCs modified with azole-based drugs were isolated for the first time and characterized by means of 1H NMR-spectroscopy as well as gel-permeation chromatography (GPC).

Polyureas (PUs) have already found wide practical applications, and various methods of their synthesis have been reported. In this manuscript, we wished to report the very first mechanochemical approach towards aromatic PUs via reactions between isomeric 2,2′-, 3,3′-, and 4,4′-diaminobiphenyls and triphosgene under solvent-free conditions following ball-milling. By using this synthetic approach, both PUs and azomethine-capped Pus were obtained. The fluorescence response of the above-mentioned PUs towards various anions in solutions were studied and selective fluorescence responses towards the hydroxyl and fluoride anions were observed.

Methods for the remote detection of warfare agents and explosives have been in high demand in recent times. Among the several detection methods, fluorescence methods appear to be more convenient due to their low cost, simple operation, fast response time, and naked-eye-visible sensory response. For fluorescence methods, a large variety of fluorescent materials, such as small-molecule-based fluorophores, aggregation-induced emission fluorophores/materials, and supramolecular systems, have been reported in the literature. Among them, fluorescent (bio)polymers/(bio)polymer-based materials have gained wide attention due to their excellent mechanical properties and sensory performance, their ability to recognize explosives via different sensing mechanisms and their combinations, and, finally, the so-called amplification of the sensory response. This review provides the most up-to-date data on the utilization of polymers and polymer-based materials for the detection of nitroaromatic compounds (NACs)/nitro-explosives (NEs) in the last decade. The literature data have been arranged depending on the polymer type and/or sensory mechanism.

Cyanide ions are known to be lethal for insects and mammals and harmful for the environment, and new methods for their selective detection are in high demand. Herein, the mechanosynthesis of simple Schiff’s bases-based probes S1–S3 for visual detection of CN⁻ anion is reported. These probes were obtained by means of a reaction between isomeric 4,4-, 3,3- and 2,2-diaminobiphenyls and 4-nitrobenzaldehyde under ball milling conditions. The probes showed high selectivity and sensitivity toward CN⁻ anion via a dramatic “yellow-to-dark purple” color change with a detection limit of 26 × 10³, 8.7 × 10³ and 14 × 10³ ppm for S1–S3, respectively. The proposed mechanism of the detection suggests the deprotonation of a proton from an imine moiety, followed by the formation of charge transfer complexes (CTC).

Mechanochemically induced methods are commonly used for the depolymerization of polymers, including plastic and agricultural wastes. So far, these methods have rarely been used for polymer synthesis. Compared to conventional polymerization in solutions, mechanochemical polymerization offers numerous advantages such as less or no solvent consumption, the accessibility of novel structures, the inclusion of co-polymers and post-modified polymers, and, most importantly, the avoidance of problems posed by low monomer/oligomer solubility and fast precipitation during polymerization. Consequently, the development of new functional polymers and materials, including those based on mechanochemically synthesized polymers, has drawn much interest, particularly from the perspective of green chemistry. In this review, we tried to highlight the most representative examples of transition-metal (TM)-free and TM-catalyzed mechanosynthesis of some functional polymers, such as semiconductive polymers, porous polymeric materials, sensory materials, materials for photovoltaics, etc.

Three efficient synthetic approaches towards new azomethine- and terpyridine-containing 2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (diketopyrrolopyrrole, DPP) based polymers, such as P1 and P2, are reported. The first approach involves the Pd-catalyzed synthesis via two- or three-component Suzuki or Stille cross-coupling reaction in solution. The second approach involves Pd-catalyzed Suzuki cross-coupling reaction under ball-milling conditions. And, finally, the third approach involves Pd-free condensation reaction under ball-milling conditions. The newly obtained polymers exhibited absorbance around 700 nm and emission around 900 nm, and, thus, these polymers are considered to be NIR-fluorophores.