Chemical Reports

Clarifying Aromaticity and Delocalization with the Principle of π-Electron Pair Interaction (PEPI)

Hai-Feng Ji — 2025-11-12

Valence bond (VB) theory and Molecular Orbital (MO) theory are foundational approaches to understanding chemical bonding. While MO theory describes delocalized orbitals across the molecule and offers quantitative rigor, VB theory aligns closely with classical chemical concepts, using localized bonds and hybridization for intuitive understanding. However, VB theory’s treatment of delocalized systems, such as aromatic compounds, relies on resonance structures, which are less efficient and may cause misconceptions compared to the methodology of MO theory. To address this, the Principle of π-Electron Pair Interaction (PEPI) is introduced as a heuristic framework to extend the qualitative power of VB theory. A visual guide is provided by PEPI to aid in understanding when π-electrons may resist delocalization due to pairing constraints. The model is intended to complement MO theory and is presented not as a physical principle, but as an interpretive aid that offers clarity in systems such as butadiene, benzene, and selected pericyclic reactions. It is demonstrated how PEPI can illuminate concepts such as aromaticity, antiaromaticity, misinterpretations of resonance, and stereoelectronic trends in a conceptually accessible manner. PEPI proposes that electron spin should be taken into account when evaluating resonance structures, particularly in the context of aromaticity. By reframing PEPI as a pedagogical tool, alignment is achieved with quantum mechanical models while the intuitive appeal of VB theory is preserved.

RETRACTED ARTICLE: An Easy Method to Non-Destructively Separate the Strands of a Circular Duplex Plasmid Chromosome: A Preliminary Report

Ken Biegeleisen — 2025-09-06

At the request of the author, this article is hereby retracted from Chemical Reports.
Reason for Retraction
1. Methodological Flaw: The reported electrophoretic separation of plasmid pBR322 strands was based on a unique 2-step denaturation procedure. Subsequent investigations revealed that the bands observed were not the top and bottom strands of pBR322, as originally claimed.
2. Critical Oversight: The experimental outcome was irreproducible due to unanticipated RNase A treatment of the DNA samples, which removed the mRNA binding sites essential for the proposed separation mechanism.
3. Research Integrity: To prevent further dissemination of potentially misleading findings, the authors voluntarily requested retraction.
Ethical Compliance
This retraction follows COPE guidelines (Section 4.11) and has been approved by the Editorial Board of Chemical Reports.

Synthetic and Spectroscopic Exploration of Haloindole Carboxaldehydes toward the Design of Bioactive Heterocyclic Architectures

leena Bharadwaj — 2025-09-05

The quest for novel bioactive heterocyclic frameworks continues to be a focal point in modern organic and medicinal chemistry. In this context, haloindole carboxaldehydes have emerged as valuable and versatile synthetic intermediates due to their electron-rich indole core, electrophilic aldehyde function, and tunable halogen substituents. This study presents a comprehensive synthetic and spectroscopic investigation of haloindole carboxaldehydes, aiming to harness their reactivity for the rational design and construction of structurally diverse heterocyclic compounds with potential pharmacological relevance. A series of halogenated indole-3-carboxaldehyde derivatives were synthesized via regioselective halogenation, followed by formylation under Vilsmeier–Haack conditions. Their structures were elucidated and confirmed through extensive spectroscopic characterization, including ¹H NMR, ¹³C NMR, FT-IR, UV–Vis, and mass spectrometry. Furthermore, the influence of different halogen atoms (Cl, Br, I) on the reactivity and electronic behavior of the aldehydes was systematically evaluated using electron spin resonance (ESR) and high-performance liquid chromatography (HPLC) analyses. The synthetic utility of these haloindole aldehydes was further demonstrated through their condensation with active methylene and amino compounds, facilitating the formation of fused heterocyclic systems such as β-carbolines, indolylpyrazoles, and oxazoles. Preliminary in silico screening of the resulting scaffolds revealed promising drug-likeness profiles and potential interactions with biological targets, highlighting their value in drug discovery. This work underscores the significance of haloindole carboxaldehydes as multifunctional building blocks for the development of complex molecular architectures with potential applications in therapeutic chemistry.

Photocatalysis of Giemsa Dye: An Approach towards Biotechnology Laboratory Effluent Treatment

leena Bharadwaj — 2025-09-01

Present investigation analyzes various water quality parameters after TiO₂ assisted photocatalytic degradation of Giemsa Dye in aqueous suspension. Significant changes were noted in alkalinity, turbidity, hardness, nitrate, calcium ion concentration, chloride ion concentration, magnesium ion concentration, COD, BOD, sulfate ion concentration, temperature and pH. At pH 2 investigated parameters were found within the WHO standards of drinking water. Environmental risk assessment reveals that beside photocatalytic treatment, waste disposal methodology still needs to be accompanied with secondary treatment of water.

An Analysis of TiO₂ Assisted Photocatalytic Degradation of Nigrosine Dye

Leena Bharadwaj — 2025-05-27

This study examined the photocatalytic degradation of Nigrosine Dye (25 ppm) in aqueous solution using TiO₂ nanoparticles under sunlight irradiation. The optimal degradation efficiency of 70.23% was achieved at pH 6 after 4 hours of treatment. Comprehensive water quality analysis revealed significant alterations in parameters including alkalinity, turbidity, hardness, nitrate, calcium, magnesium, COD, BOD, sulfate, temperature and pH, with water hardness exceeding WHO drinking water standards. HPTLC analysis demonstrated successful dye degradation through reduced peak numbers in densitograms. Environmental risk assessment showed: 1) no antibacterial activity against E. coli at 10 ppm concentration; 2) improved seed germination rates (85% at pH 5.4 and 80% at pH 7) compared to untreated dye (10%), though slightly lower than control (96.25%). The results indicate TiO2 photocatalysis effectively degrades Nigrosine Dye but requires further optimization to address residual hardness and minor phytotoxicity observed at neutral pH conditions.

Comparative study of the combustion properties of briquettes produced from blends of mung beans shell, uncarbonized and carbonized sawdust

Chinyere E. Umeocho — 2024-05-13

In this research, the combustion properties of the briquette produced by blending mung beans shell (MBS) with carbonized danta wood sawdust was compared with that of the briquette produced by blending MBS with uncarbonized danta wood sawdust. The briquettes wereproduced atdifferentsawdust to biomass ratios (100%:0, 70%:30%, 50%: 50%, 30%: 70% and 100%:0). Cassava starch was used as a binder. Proximate analysis (moisture content, ash content, volatile matter and fixed carbon) and combustion properties (calorific value, ignition time, burning time, burning rate, specific fuel consumption and thermal efficiency) were calculated using standard methods. The results of the analyses showed that 100% sawdust briquette samples had the lowest moisture content, 4.74±0.00 for carbonized sawdust and 6.76±0.02 for uncarbonized sawdust.100% uncarbonized and carbonized sawdust briquette samples had a fixed carbon of 68.93±0.02 and 87.46%, Ash content:3.70±0.00% and 2.18±0.04%,volatile matter: 20.61±0.00 and 5.61±0.04 and calorific value: 29.401±0.0 MJ/Kg and 32.532±0.05 MJ/Kg respectively.The ignition time increase with increase in biomass load for uncarbonized sawdust samples and decrease with increase in biomass load for carbonized sawdust briquette samples. The burning time decreased from 86±0.57mins (70% sawdust + 30% biomass) to 70±0.57mins (100% biomass) for the carbonized sawdust briquette samples and for the uncarbonized, it ranged from 68±0.00 (70% sawdust + 30% biomass) to 71.6±0.57 mins (30% sawdust + 70% biomass) and then dropped to 68±0.57(100% biomass load). The burning rate decreased in carbonizedbriquette samples and increased in uncarbonized briquette samples with increase in biomass load. The specific fuel consumption for carbonized and uncarbonized sawdust briquette sample decreased with increase in MBS load. 100% carbonized and uncarbonized sawdust briquette samples had a thermal efficiency of 8.78 and 16.47 respectively. It can be concluded that blend of carbonized sawdust and mung beans shell will make a better fuel due to better combustion properties than the uncarbonized sawdust samples.

Concentration levels and pollution status of selected heavy metals in active dumpsites in Port Harcourt, Rivers State, Nigeria

Victor Uchenna Okechukwu — 2024-03-05

This study was carried out to assess the extent of concentration exposure of As, Cu, Cr, Ni and Mn in the soils of five active dumpsites located at (Eliozu, Oyibo, Eneka, Eleme and Woji) in the city of Port Harcourt Rivers State, Nigeria to evaluate the pollution indices of heavy metals. Soil samples were collected randomly at the quadrant from the dumpsite while control samples were collected from farmland 25 km away from the dumpsite. Some physiochemical parameters (pH, TOC and CEC) of the soils were evaluated using standard techniques, while the heavy metal concentrations were evaluated using Atomic Absorption Spectroscopy (AAS). The pollution levels of soil heavy metals were assessed using several pollution indices. The mean concentration of heavy metals (mg/kg) ranged between As (ND – 0.45), Cr (ND – 2.21), Cu (6.05 – 51.87), Mn (3.24 – 37.91), Ni (ND – 13.50) across the studied dumpsites. The heavy metal levels in soil samples observed were in the order of Cu > Mn > Ni > Cr > As (Eleme), Cu > Mn > As > Ni > Cr (Eliozu), Cu > Mn > Ni > Cr > As (Eneka), Cu > Mn > Cr (Oyigbo), Cu > Mn > Ni > Cr > As (Woji), Cu > Mn > Ni > Cr > As (Control Site). The pH results were relatively acidic across the studied dumpsites ranging from 5.7±0.58 to 6.63± 0.02, while the TOC levels were low to moderate showing no wide disparity in the values. The Cation exchange capacity (CEC) showed a range of 13.98±0.186 (Eneka) to 20.98±0.061 cmol/kg (Woji) across the studied dumpsites. The Igeo values except for Ni, Cu and Mn at Eneka dumpsite, Cr and As in all the studied dumpsites revealed moderate to heavy contamination. Pollution load index (˃ 1) was in the studied dumpsites which implies that there is heavy metal pollution across the studied dumpsites. Anthropogenicity indicates that human activity is mostly responsible for the increase in metals in the studied area. Low ecological risk indices for the heavy metals (Ni, Cu, Cr, Mn, As) were found in all the sampling locations except for copper in Oyibo dumpsite. According to the findings, there is a low to moderate level of heavy metal pollution in the soils from the dumpsite, which can deteriorate the food ecosystem if adequate measures are not put in place.

Chemical fractionation and mobility factor of some heavy metals in refuse dumpsite soil in Awka Metropolis, Anambra State, Nigeria

Ogochukwu J. Okakpu — 2024-02-02

The geochemical forms of some heavy metals in refuse dump soils at Agu-Awka, Awka metropolis was studied in order to assess the mobility and bioavailability of the metals and hence their potential environmental risk. Exchangeable fraction (F1) contained the % fraction of 13.23% for Cd, 17.43% for Cr, 14.63% for Pb, 12.40% for Ni, 25.34% for Zn and 15.92% for Mn and these are in the order of Zn ˃ Cr ˃ Mn ˃ Pb ˃ Cd ˃ Ni. The carbonate fraction (F2) contained the % fraction of 17.08% for Cd, 17.84% for Cr, 9.20% for Pb, 28.32% for Ni, 13.76% for Zn and 8.49% for Mn and these are in the order of Ni ˃ Cr ˃ Cd ˃ Zn ˃ Pb ˃ Mn. Lead was predominantly associated with organic fraction with a result of 42.64% followed by chromium and manganese with the values of 22.48% and 20.00% respectively. The organic bound metals were in the abundance trend of Pb ˃ Cr ˃ Mn ˃ Cd ˃ Ni ˃ Zn. The highest values of metal in Fe-Mn oxide phase was manganese with a value of 32.18%, followed by cadmium with the value of 21.76%. The values of the other metals bound to this phase were 17.52%, 16.64%, 13.99% and 12.90% for Zn, Ni, Cr, and Pb respectively. Zinc with the value of 32.20% was predominantly associated with the residual fraction. The other metals bound to this phase had their values to be 30.13% for cadmium, 28.24% for chromium, 20.61% for lead, 29.41% for nickel and 23.37% for manganese. The mobility factor values of the metals were relatively low and they followed the order of Ni > Zn > Cr > Cd > Mn > Pb. That notwithstanding, soils from studied area should be carefully monitored to prevent the release of these metals due to redox reactions which may make them available to plants through absorption.

Effect of organic manures and micronutrients on seed production of carrot (Daucus carota L.)

Asha Dhaka — 2022-12-20

The experiment was conducted during 2021-22 in rabi season. The field study to assess the effects of organic manures and micronutrients on seed production of carrot (Daucus carota L.) cv. Pusa Rudhira was carried out at Horticulture farm, SKNCOA, Jobner, Rajasthan, India. The study revealed that the application of Poultry manure @ 2.5 t/ha significantly increased the plant height (41.95 cm), Number of shoots per plant (12.71), chlorophyll content (1.11 mg/100g), days to 50% umbel initiation (134.50 days) , number of umbels per plant (17.30), number of seed per umbel (1177.35), diameter of umbel (16.71 cm), seed weight per plant (8.43 g), days to seed maturity (185.27 minimum days) and seed yield per hectare (6.24 q/ha). Similarly, the spray of ZnSO₄ @ 0.5% to the carrot crop significantly increased the plant height (40.60 cm), number of shoots per plant (12.49), chlorophyll content (1.07 mg/100g), days to 50% umbel initiation (133.51 days), number of umbels per plant (16.30), number of seed per umbel (1175.30), diameter of umbel (16.10 cm), seed weight per plant (8.39 g), days to seed maturity (184.12 days ) and seed yield per hectare (6.21 q/ha)

Extraction and analysis of back-sheet layer from waste silicon solar modules

Chitra Chitra — 2022-09-16

The back-sheet shields the solar panel from UV rays, moisture, dust, and other environmental factors. With the enormous growth of the solar industry year after year, the demand for recycling is also increasing rapidly. In the present study, the back-sheet layer was extracted from a waste crystalline silicon PV module by thermally heating the module at 130˚C temperature. Various characterization techniques, including Raman, FTIR, SEM-EDAX, XRD, and TGA, were used to examine extracted back-sheet layer properties for its reuse. The Raman and FTIR spectra of extracted back-sheet are quite similar to those of reference PET back-sheet, indicating that no significant changes in composition occurred during the extraction process. The extracted back-sheet has a composition of carbon and oxygen as witnessed from EDAX spectroscopy. The extracted back sheet maintained its semicrystalline behavior as that of the reference back sheet, observed by XRD spectroscopy. Thermogravimetric analysis revealed that the thermal stability of extracted back-sheet is up to 252˚C in the air environment and up to 315˚C in the inert environment. Thermal degradation of extracted back-sheet is a two-step process in an air environment observed by differential thermogravimetry. The observed properties of extracted back-sheet are comparable to those of commercially available back-sheet, and the same may be reused in solar and polymer industries after appropriate processing.