Methodology gaps in Chemistry

Representative open questions

Showing 30 of 248 — one per source paper, highest-quality first.

• Ultrasound-assisted adsorption of congo red dye using green synthesized silver nanoparticles coated with chitosan (2026) · doi

  The study demonstrates Chi-AgNPs adsorption of Congo Red at optimal conditions (0.025 g dosage, 5 min sonication), but does not investigate the effect of varying ultrasound frequencies, intensities, or power outputs on adsorption capacity and removal efficiency of the chitosan-coated silver nanoparticles system.

• Real-time P$$_2$$O$$_5$$ quantification in industrial phosphoric acid using laser-induced breakdown spectroscopy: a paradigm shift in process analytical chemistry (2026) · doi

  The VIP-filtered PLS model achieved improved cross-validation performance (R²CV = 0.96 vs. 0.94) by reducing wavelengths from 4711 to 3099, but the optimal VIP threshold selection methodology and whether further aggressive feature reduction below VIP > 0.5 could maintain predictive accuracy without sacrificing model robustness has not been systematically investigated.

• Mechanistic investigations of the formation of multifunctional products from the multi-generation ●OH oxidation of styrene (2026) · doi

  The fractional yields for second and third generation closed-shell products vary significantly (e.g., S26: 4.8%, S47: 26.3%, S62: 0.03%); systematic sensitivity analysis examining how experimental conditions (temperature, pressure, NOx concentration, humidity) affect these yield distributions has not been performed.

• High-Entropy Catalysts for Biomass-Derived Chemicals Valorization: Mechanisms, Applications, and Opportunities (2026) · doi

  Structure design strategies developed for high-entropy catalysts in hydrogen oxidation reactions (such as HEA aerogels with 3D interconnected open channels and nanoscale distorted structures) have not been systematically transplanted to or validated for biomass valorization reactions. The correlation between aerogel morphology, macroscale nanoscale property retention, and catalytic performance in glucose and glycerol conversion requires experimental investigation.

• Green Dispersive Liquid–Liquid Microextraction Using an Octanol-Menthol-Based Deep Eutectic Solvent for Sensitive UV–Vis Determination of Rhodamine B in Food and Water Samples (2026) · doi

  The method's use of methanol as a diluting solvent compromises full conformity to green chemistry standards due to its toxicity and volatility; alternative green diluting solvents compatible with the octanol-menthol DES extraction should be investigated to achieve complete green analytical chemistry compliance.

• Photochemistry and photophysics of transition metal complexes: Quantum chemistry (2015) · doi

  The QM/MM model for Ru(II) dppz complexes intercalated in DNA requires at least two base pairs in the QM part to correctly assign the character of ILdppz states, but convergence of lowest triplet states has only been achieved for [Ru(bpy)2(dppz)]2+ and [Ru(tap)2(dppz)]2+; systematic convergence studies across all three complexes (phen, tap, bpy substituted) with varying QM/MM frontier definitions remain incomplete.

• The role of the bis-trimethylsilylamido ligand, [N{SiMe3}2]−, in main group chemistry. Part 1: Structural chemistry of the s-block elements (2015) · doi

  The mechanism for formation of the tetrametallic complex [Fe(N{SiMe3}2)2Li(bta)]2 (258) via the 'intercepted ladder' structure was only postulated rather than experimentally verified. Direct mechanistic investigation using spectroscopic or kinetic techniques is required to confirm the proposed pathway involving initial {Li(bta)}2 formation and its interaction with iron amide species.

• Functional nanocomposites for energy storage: chemistry and new horizons (2020) · doi

  Replacing carbon with group 14 elements in polymer chains to tailor ionic polarization shows theoretical promise but presents significant synthesis challenges; the specific synthetic routes, reaction conditions, and scalability barriers for producing such modified polymers for nanocomposite capacitors remain unaddressed.

• Cyclooligophosphanes and their coordination chemistry (2021) · doi

  While catalytic dehydrocoupling methods for primary phosphines are established with iron(II), zirconium, and N-heterocyclic carbene mediators (references 39, 44, 45, 43), the selectivity and regioselectivity of cyclophosphane ring closure when using substituted phosphines with mixed organic groups (alkyl/aryl combinations) has not been systematically investigated.

• A review: recent progress of piezoelectric effect coupled photocatalytic reaction: diverse mechanisms, system/structure design, characterization and application (2026) · doi

  Most high-precision spectroscopic and microscopic characterization instruments (such as Electron Paramagnetic Resonance and X-ray Photoelectron Spectroscopy) are limited by small sample chamber environments incompatible with mechanical force conditions required to induce piezoelectric effects; dedicated in situ characterization platforms compatible with ultrasonic excitation and flowing media have not been constructed.

• Christmas chemistry A–Z (2014) · doi

  The vanilla section notes a 100-fold discrepancy between natural vanilla extraction (100t/year) and global demand (20,000t/year), with most being chemically synthesized, but does not investigate the specific chemical synthesis pathways used commercially or compare the sensory/chemical profile differences between naturally extracted and synthetically produced vanillin at equivalent concentrations.

• Olympian colour chemistry (2012) · doi

  Multi-dye formulations for achieving neutral grey and brown lens shades require balancing up to six different photochromic dyes with complementary absorption spectra and kinetics. The paper lacks systematic guidelines for predicting which combinations of dihetarylethene, spirooxazine, and naphthopyran structural modifications (electron donor positioning, halogen substitution, alkoxy/amino groups) will optimize neutral colour without fatigue or kinetic mismatches.

• Biosensors: Enzyme Immobilization Chemistry (2018) · doi

  The affinity-based immobilization using concanavalin A or boronic groups is described as advantageous for controlling enzyme active site orientation, yet the paper provides no comparative data on active site orientation efficiency between glycan-mediated immobilization and other methods (covalent bonding, entrapment, polyelectrolyte multilayers) in actual biosensor applications.

• WITHDRAWN: Combinatorial Chemistry Online Volume 15, Issue 11, November 2013 (2013) · doi

  The iterative ligation approach for polypeptide synthesis using bis(2-sulfanylethyl)amido (SEA) peptide segments reported by Raibaut et al. has demonstrated efficiency for large polypeptides, but systematic optimization of coupling efficiency, segment length constraints, and compatibility with post-translational modifications in combinatorial contexts is absent.

• Methyl 2-deoxy-3,5-di-O-p-toluoyl-α-d-ribofuranoside: isolation, crystal structure and conformation (2026) · doi

  The crystal structure and conformational analysis of methyl 2-deoxy-3,5-di-O-p-toluoyl-α-D-ribofuranoside has been characterized, but comparative conformational studies with structurally similar 2-deoxy ribofuranose derivatives bearing different acyl protecting groups (beyond p-toluoyl and p-nitrobenzoyl) are lacking, limiting understanding of how protecting group substitution patterns influence sugar ring pseudorotation.

• Transmetallation Reaction of Alkali and Alkaline-earth Metal Ions in Supramolecular Complex of [{Au6Cd3(tdme)2(D-pen)6}Cd4Na4](NO3)12 (2026) · doi

  The study only examined transmetallation reactions with alkali metals (Na, K, Cs) and alkaline-earth metals (Sr) in the supramolecular Au₆Cd₃ cage framework. Transmetallation behavior with transition metal ions possessing accessible d-orbitals (e.g., Zn²⁺, Cu²⁺, Ni²⁺) at the metal-linker position should be systematically investigated to test whether d-orbital availability enables substitution at the coordinate CdII centers.

• Synthesis of Tetravalent Boron Complexes with Pyrazolone-Based Ligand and their Drug-Likeness (2026) · doi

  The synthesis and characterization of tetravalent boron complexes with 2-isopropoxy-1,3,2-benzodioxaborole and 5-methyl-2-phenyl-4-(2-phenylhydrazinylidene)-2,4-dihydro-3H-pyrazol-3-one was reported, but metabolic stability studies using liver microsomes or recombinant cytochrome P450 enzymes were not conducted to assess phase I/II biotransformation pathways of these specific boron-pyrazolone coordination compounds.

• Physical Organic Chemistry (POC) Makes Chemistry a Science: A Personal Reflection on POC (2016) · doi

  The Big Data approach for chemical discovery is proposed conceptually but lacks concrete implementation details for chemistry datasets. Specific protocols are needed for mining historical chemical databases, literature archives, and synthesis records to identify previously unobserved correlations and cause-effect relationships in organic reaction mechanisms.

• Chitosan and radiation chemistry (2010) · doi

  The radiolytic properties of chitosan show potential for DNA and membrane protection through free radical conversion, but the paper lacks detailed mechanistic characterization of which specific terminal products of chitosan radiolysis are responsible for radioprotection and their relative contributions to overall protective effects.

• Introduction to Surface Chemistry Essentials (2013) · doi

  The paper identifies that no direct measurement procedure currently exists to characterize self-assembly monolayer (SAM) structures, limiting empirical verification of molecular arrangement at interfaces. Developing experimental techniques to directly measure SAM composition and orientation on solid substrates would advance understanding of interfacial organization beyond indirect surface tension measurements.

• Subject Index (2011) · doi

  The paper references room temperature ionic liquids (RTILs) as replacements for conventional organic solvents in reversed-phase liquid chromatography (RP-LC) with high temperature thermal gradients (pages 129-130, 131t), but does not establish quantitative green chemistry metrics (energy consumption, waste generation, operator exposure) comparing RTILs to traditional mobile phases under identical separation conditions.

• Basic Organometallic Chemistry (2016) · doi

  The paper describes tetrameric and hexameric forms of methyllithium identified through NMR and crystallography, but does not explore the kinetic stability or interconversion mechanisms between these oligomeric forms under different solvent and temperature conditions.

• Initial organotin chemistry (2014) · doi

  The mechanism of polystannane degradation under light exposure to form cyclic oligostannanes from [(C2H5)2Sn]n has not been experimentally validated or quantified; the specific wavelength dependencies and degradation kinetics require investigation.

• Using quantum chemistry to estimate chemical shifts in biomolecules (2020) · doi

  The level of theory and basis set dependence documented in references [26] for isolated protein fragments has not been extended to investigate how different functional (B3LYP, OPTX, etc.) and solvation model choices affect chemical shift predictions in RNA hairpin structures and DNA-protein complexes.

• Chemistry of Carbon and Hydrogen (2019) · doi

  The text describes carbon allotropes (diamond, graphite, fullerene, coal, charcoal, coke) but does not address the synthesis parameters, yield optimization, or structural characterization methods required to controllably convert between amorphous forms (charcoal, lampblack) and crystalline allotropes under specific temperature and pressure conditions.

• Bis (N-Heterocyclic Carbene) Palladium Complex Immobilized Onto Fe3o4@Sio2 as a Catalyst for Sonogashira (Amine/Copper Free) and Hiyama Coupling of Arbr/Cl in Green Media (2026) · doi

  The catalyst recyclability studies demonstrate efficient reuse up to 6 cycles, but a pronounced efficiency drop occurs at the seventh cycle. The specific mechanism of catalyst deactivation—whether caused by Pd leaching, support degradation, or NHC ligand decomposition—requires investigation to enable extended operational lifetime of the Fe3O4@SiO2-supported Pd-NHC heterogeneous catalyst.

• Coordination chemistry of poly(thioether)borate ligands (2010) · doi

  The mechanism for stepwise formation of [(PhTttBu)Ni]2(μ-O)2 from [PhTttBu]Ni(CO) has been proposed based on optical and EPR spectral evidence of the 1:1 intermediate, but direct kinetic characterization of the dimerization step and quantitative rate constants for the transition from monomeric [PhTttBu]Ni(O2) to dimeric bis-μ-oxo product are lacking.

• Evaluation of Octaethyl-7,17-dioxobacteriochlorin as a Ligand for Transition Metals (2020) · doi

  The metal insertion kinetics were monitored only for zinc acetate complexation with octaethyl-7,17-dioxobacteriochlorin under reflux conditions in DMF. The reactivity of other transition metals (copper, nickel, cobalt, iron) with this dioxobacteriochlorin ligand under identical or varied conditions (temperature, solvent, pH) has not been systematically evaluated.

• Coordination chemistry of tris(azolyl)phosphines (2018) · doi

  The triazolylation reaction using OP(1,2,4Tz)3 has been conducted in three different solvent systems (acetonitrile, dichloromethane, and pyridine) with varying base conditions and product yields (up to 60% in pyridine), but no systematic solvent-base screening or mechanistic investigation has been reported to optimize reaction conditions or understand why pyridine occasionally produces only pyridinium salts as side products.

• Quinolines, a perpetual, multipurpose scaffold in medicinal chemistry (2021) · doi

  The SAR study of quinoline derivatives revealed that C-6 position substitution with bromine showed lower IC50 values compared to C-7 analogues, but systematic investigation of other halogen substitutions (fluorine, chlorine, iodine) at C-6 and C-7 positions of the quinoline nucleus has not been conducted to establish a comprehensive SAR profile for halogenated quinolines.