Validation gaps in Chemistry

Representative open questions

Showing 30 of 153 — one per source paper, highest-quality first.

• Bi-Polar Bioenergetic Intervention via a Pathology Self-Adaptive Single-Atom Nanocatalyst for Diabetic Tumor Postoperative Management (2026) · doi

  The PtSNC nanocatalyst demonstrated 98.5% tumor inhibition in a B16F10 melanoma model, but efficacy testing is limited to a single tumor type. The generalizability of bi-polar bioenergetic intervention via single-atom platinum catalysis to other solid tumors (e.g., breast, lung, pancreatic carcinomas) with distinct metabolic profiles remains uncharacterized.

• 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 current LIBS calibration for P2O5 quantification was established using volumetrically diluted industrial stock solutions with representative impurities (Fe, Al, Mg, silicates), but the model has not been validated against dynamic matrix effects encountered in active wet-process phosphoric acid production streams, including acid viscosity fluctuations and suspended solids such as calcium sulfate (gypsum).

• PRONIOSOMAL DRUG DELIVERY SYSTEMS: FABRICATION APPROACHES, MECHANISTIC INSIGHTS, AND MULTIFUNCTIONAL THERAPEUTIC APPLICATIONS (2026) · doi

  Metformin-incorporated proniosomes claim reduced gastrointestinal side effects and improved absorption with controlled release; however, direct comparison studies measuring gastrointestinal side effect incidence, absorption kinetics, and drug release profiles between proniosomal metformin and marketed extended-release metformin formulations in humans or appropriate GI models are absent.

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

  Bicyclic peroxide radical (BPR) formation and subsequent reactions with HO2 and NO are proposed as pathways to second-generation products; experimental confirmation of BPR intermediates through spectroscopic detection (e.g., infrared, mass spectrometry) or indirect characterization methods is currently unavailable.

• Donor-length engineering in directly linked covalent heptazine frameworks for photocatalytic H2O2 Production (2026) · doi

  The EPR spin-trapping experiments for ·OH detection using DMPO were conducted in purely aqueous solution under Ar-bubbling conditions; the detection and quantification of ·OH radicals in the presence of competing solutes (e.g., humic acids, inorganic ions) and at varying dissolved oxygen concentrations for H2O2 photosynthesis on heptazine catalysts have not been systematically studied.

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

  While particle size engineering has been identified as critical for tuning active site exposure, lattice distortion degree, and mass transfer efficiency in high-entropy catalysts, the specific size ranges (nanometer scale thresholds) that optimize configurational diversity and entropy effects for individual biomass valorization reactions (HMF, furfural, glucose, glycerol transformations) have not been systematically characterized.

• 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 UV–Vis spectrophotometry detection in the DLLME-OCT-MEN-DES method exhibits limited selectivity in complex matrices with overlapping absorbance characteristics; complex samples with high matrix interference, such as food items with vibrant colours or high organic loads, were not included in this validation study.

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

  The butterfly movement of ancillary ligands and accordion motion of the dppz ligand in triplet excited states have been identified computationally for [Ru(phen)2(dppz)]2+ and [Ru(tap)2(dppz)]2+, but experimental validation of these structural dynamics through time-resolved spectroscopy or X-ray crystallography of triplet states has not been demonstrated.

• 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 bioinorganic-inspired [Fe4S4] cubane cluster chemistry with amide-ligated systems includes examples with –N{SiMe3}2 ligands, but the specific structural roles and electronic effects of the bis-trimethylsilylamido ligand in modulating the redox properties of these cubanoid clusters have not been directly compared across different charge states (4+, 3+, 2+).

• Olympian colour chemistry (2012) · doi

  The paper identifies that additives intended to stabilise photochromic dyes can produce undesired consequences such as altering photocolouration kinetics or generating residual colour in the non-activated state, but does not quantify the threshold concentrations or structural modifications of spirooxazines and naphthopyrans at which these side effects become problematic versus acceptable for commercial lens applications.

• Biosensors: Enzyme Immobilization Chemistry (2018) · doi

  While polyaniline is highlighted as superior for electron transfer mediation and signal transportation in electropolymerized biosensors, the paper does not compare its long-term stability, conductivity retention, and charge transfer capability with other conductive polymers (pyrrole, other conducting matrices) over extended biosensor operational periods.

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

  High-throughput screening of one-bead-one-compound peptide libraries using intact cells, as demonstrated by Cho et al., lacks comparative evaluation against conventional cell-free screening methods; the relative advantages and limitations of intact cell-based selection for identifying bioactive peptides versus acellular approaches remain uncharacterized.

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

  The paper presents X-ray crystallographic data for the isolated compound but does not report solution-phase NMR conformational studies or molecular dynamics simulations to validate whether the solid-state conformation observed in the crystal structure is maintained in solution, which is critical for understanding its reactivity as a glycosylation donor.

• 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 transmetallation reactions were investigated exclusively under solid-state single-crystal-to-single-crystal conditions. Whether the selectivity patterns and mechanistic insights (metal-linker exchange but not metal-center exchange) hold in solution-phase transmetallation or under different synthetic conditions (temperature, solvent, reaction time variations) remains unexamined.

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

  The study evaluated drug-likeness of tetravalent boron complexes (MPAP-1 to MPAP-6) using computational physicochemical properties against five rule sets (Lipinski, Ghose, Veber, Egan, Muegge), but did not conduct in vitro absorption, distribution, metabolism, and excretion (ADME) studies or cell-based bioavailability assays to experimentally validate the predicted oral bioavailability of these pyrazolone-based boron coordination compounds.

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

  The paper demonstrates AI-discovered chemical rules with statistical significance (p < 0.01, probability 0.90) but does not address validation mechanisms for translating these computational correlations into mechanistic insights. Methods are needed to experimentally verify whether AI-identified patterns (e.g., C-O bond effects on detonation velocity) have genuine chemical causality versus spurious correlation.

• Chitosan and radiation chemistry (2010) · doi

  Serine-type chitosan resin achieves 97.1% uranium recovery in artificial seawater and 93.0% in natural seawater through ICP-MS analysis, but the paper does not address the selectivity of this resin toward uranium in the presence of competing metal ions or its performance with different seawater salinity levels and competing anions.

• Introduction to Surface Chemistry Essentials (2013) · doi

  The paper notes that the transition region's depth from bulk fluid to gas phase remains unresolved—specifically whether density change (factor of 1000) occurs across a monolayer or multiple layers. Quantitative studies using techniques like X-ray reflectivity or neutron scattering on liquid-gas interfaces should systematically measure interfacial thickness as a function of temperature and molecular properties.

• Subject Index (2011) · doi

  The paper references membrane-based sorbent interfaces and semipermeable membrane devices (SPMDs) for extraction (pages 102-103f), but does not establish quantitative evaluation of their selectivity and sensitivity across different analyte polarities or molecular weight ranges compared to conventional solid phase extraction (SPE) and solid phase microextraction (SPME).

• Basic Organometallic Chemistry (2016) · doi

  The paper demonstrates that Zeise's salt undergoes hydrolysis and nucleophilic displacement reactions, but does not systematically compare reactivity patterns or substitution rates with other metal-alkene complexes containing different transition metals or different alkene ligands.

• Initial organotin chemistry (2014) · doi

  The equilibrium reaction between (C2H5)3SnOH and the dinuclear (C2H5)3SnOSn(C2H5)3 in response to atmospheric humidity has been proposed but not rigorously quantified; equilibrium constants and the effect of temperature and humidity gradients on this condensation reaction need experimental determination.

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

  The fragment-based QM/MM approaches for NMR chemical shift calculations (AFNMR, fragment density functional theory) have not been systematically compared across different fragmentation schemes and boundary treatments for large protein complexes exceeding 300 amino acids.

• 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

  Catalyst loading optimization (entries 14-17 in Table 1) shows that reducing catalyst from 20 mg drastically decreases yield, but the specific minimum active site concentration required for efficient Sonogashira coupling and the relationship between Fe3O4@SiO2 support particle size and catalytic turnover frequency are not reported. Characterization of active site density and heterogeneity across catalyst batches would validate reproducibility.

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

  The side-on [PhTtAd]Ni(O2) complex is described as potentially lying on the superoxo-to-peroxo continuum based on DFT-derived O–O distances, but experimental methods to definitively distinguish between nickel(II)-superoxo versus more activated peroxo character through spectroscopic techniques beyond EPR and computational modeling have not been demonstrated.

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

  The successive-standard-addition UV-vis titration method employed for kinetic monitoring was limited to wavelengths with r² > 0.998 linearity. Extension of this quantitative approach to other spectroscopic techniques (HPLC, mass spectrometry, NMR) for concurrent tracking of metal insertion into octaethyl-7,17-dioxobacteriochlorin has not been explored.

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

  The tris(sulfide) variant SP(1,2,4Tz)3 reportedly affords higher yields in phosphorylation reactions compared to the oxide OP(1,2,4Tz)3, but comprehensive comparative studies across multiple substrate classes (nucleosides, amino alcohols, nucleotide precursors) and purification methods have not been conducted to establish when the sulfide form is preferentially applicable over existing phosphorylation agents.

• Gazania rigens (L.) gaertn leaf extract-inspired innovative synthesis of silver nanoparticles and promising applications as antibacterial and cytotoxic agents (2026) · doi

  The comparative selectivity between G-AgNPs and established AgNP formulations requires quantitative assessment across multiple cancer cell lines. While the paper demonstrates IC50 values for MDA-MB-231 breast cancer cells versus MCF-10A non-cancerous epithelial cells, no head-to-head comparison with chemically synthesized AgNPs or other green-synthesized formulations is provided to establish whether Gazania rigens-derived nanoparticles exhibit superior cancer cell selectivity.

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

  Molecular docking studies identified hydrogen bonding and hydrophobic forces as responsible for quinoline peptide interactions with DNA-gyrase, but experimental validation through isothermal titration calorimetry (ITC) or surface plasmon resonance (SPR) binding kinetics has not been performed to quantify the binding affinity constants (Kd values).

• My journey in the CO2-chemistry wonderland (2017) · doi

  Metal oxide catalysts for selective epoxidation of olefins show unpredictable performance dependent on the 'mode of being' of the oxide on the catalyst surface, which varies with synthetic procedure and uncontrolled factors. Systematic characterization studies are needed to identify and control the surface oxide structure parameters that determine whether the catalyst produces selective epoxidation (100% propene oxide) versus combustion or aldehyde/ketone formation.

• Resonance-enhanced multiphoton ionization time-of-flight mass spectrometry for the real-time analysis of a retronasal aroma compound from a cumin sandwich (2026) · doi

  The proposed logistic function fitting approach for extracting quantitative release times (γ1, γ2) from time profiles exhibiting breath-synchronized fluctuations has not been validated against independent methods or on other aroma compound classes beyond p-cymene in cumin sandwiches using REMPI-TOFMS.