Donor-acceptor Interactions Research Articles

Solanum tuberosum leaf extract as an eco-friendly corrosion inhibitor for Q235-steel in HCl medium: Experimental and theoretical evaluation

Solanum tuberosum leaf extract (STLs), used as a biodegradable corrosion inhibitor, was prepared to mitigate the corrosion rate of Q235 steel in HCl medium. The active inhibitory components existing in STLs were tracked by Fourier transform infrared spectroscopy. Electrochemical measurements, morphological characterization and contact angle tests were combined to evaluate the anti-corrosion performance of STLs at various concentrations and different temperatures, and the results show that the addition of STLs can evidently magnify the charge transfer resistance, expand the double layer capacitance at electric/solution interface, and simultaneously reduce the corrosion current density of Q235 steel in HCl medium with the maximum inhibition efficiency of 91.89 %. The adsorption behavior of STLs on steel was investigated using X-ray photoelectron spectroscopy and adsorption models. It is revealed that the molecules of STLs spontaneously bind to the substrate through chemical and physical action, forming a protective layer to block the diffusion pathway of harsh ions. Furthermore, theoretical calculations confirm that Solanum tuberosum leaves components were adsorbed on steel substrates through donor-acceptor interactions.

The adsorption mechanism and optimal dosage of walnut shell biochar for chloramphenicol

Biochar derived from biomass pyrolysis has proven to be an excellent material for pesticide adsorption and can be used as soil amendment for pesticide non-point pollution. However, the adsorption and desorption mechanisms for certain biochar and pesticide are still unclear. In this study, we investigated the properties of biochar derived from walnut (Juglans regia L.) shell (WSB), and used batch equilibrium method to investigate the adsorption and desorption behavior for chlorantraniliprole (CAP). The physical-chemical analysis showed that there were mainly lignin charcoal of alkyl carbon, methoxyl carbon, aromatic carbon, and carboayl carbon as the primary carbon compounds of WSB. The π - π electron donor acceptor interaction, electrostatic interaction, and hydrogen bond were the primary adsorption mechanisms of the WSB adsorption. Batch equilibrium study under 298 K showed that WSB application in the soil significantly improved the adsorption ability for CAP, and the adsorption behavior was a mono-layer adsorption process as Langmuir model fitted the adsorption isotherm data better than the Freundlich model. While Freundlich model analysis showed that WSB addition to the soil changed the isothermal adsorption line from the S style to the L style. The spontaneous degree reaction of sorbents from strong to weak was in the following order: 5%-WSB >7%-WSB >10%-WSB >1%-WSB >3%-WSB > soil > WSB, and the maximum application effect was achieved at 5 % (m/m) WSB dosage mixed with the soil. Therefore, we considered that WSB addition in soil increased its CAP adsorption capacity, and 5 % (m/m) WSB application was the best choice for CAP pollution control. These data will contribute to the adsorption mechanism and the optimal use dosage of WSB for CAP pollution control.

Mechanism of tetracycline sorption on carbon-bentonite

Antibiotics increased industrial production is the reason of their occurrence in wastewater, soils, groundwater, and drinking water. In this regard, treating the environment for pharmaceuticals is one of the urgent environmental challenges. Synthesis of adsorbents using different types of raw materials by the methods of mechanochemical activation makes it possible to significantly increase their sorption capacity due to the accumulation of various kinds of defects in the crystal structure of the adsorbent. We obtained the bentonite-carbon composite using roller-ring vibratory mill with coal-bentonite ratio of 30 : 70 and 50 : 50. However, the nature of the interaction between carbon and bentonite correlates with changes of surface area and porosity. The porous structure parameters of the samples show the mechanochemical activation of the mixture involves their components interactions. The authors studied the structural and chemical changes during the modification of bentonite with activated carbon by analysing the vibrational spectra of carbon, initial, and modified aluminosilicate samples. According to infrared spectroscopy of adsorbents, absorption bands characteristic of Si-O-C bond vibrations occurred. The paper investigates the sorption capacity of mechanochemically modified natural clay mineral Dash-Salakhli bentonite towards tetracycline hydrochloride. Research investigates the kinetics of the process and rapid sorption of tetracycline. The paper provides possible mechanisms of chemisorption due to donor-acceptor interaction and ion-exchange processes.

Investigation of spectroscopic characterization, crystal structure, and antitumor activity of a novel 2ATP molecule

In this section, the spectroscopic characteristics of 2-amino-toysl-pyridine (2ATP) are fully examined, using both experimental and computational investigations guided by density functional theory (DFT). It will facilitate our computational research using the B3LYP approach to use the basis set 6–311++G(d,p). Comprehensive assignments of vibrational modes were obtained from the vibrational spectra, which comprised FT-Raman and FT-IR spectroscopy and were recorded in the region of 3500–400 cm−1 and 4000–500 cm-1, respectively, using the Vibrational Energy Distribution Analysis (VEDA) approach. The net atomic charges inside the molecule were ascertained by using Mulliken population analysis, natural atomic charges, and electrostatic potentials (CHELPG). The structural conformations of 2ATP were determined using NMR spectroscopy in a CDCl3 solvent. The donor-acceptor interactions of the 2ATP molecule at the 6–311++G(d,p) level were studied by means of a Natural Bond Orbital (NBO) study. Studies of the ultraviolet (UV) spectrum in ethanol were used to assess the effects of the solvent. An assessment was made of the energy difference between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) in order to understand charge transfer processes that suggest the molecule may have biological activity. Molecular electrostatic potential (MEP) surfaces were used to predict the nucleophilic and electrophilic sites in molecules. The non-covalent interactions were evaluated using the reduced density gradient (RDG) approach. The Multiwfn software was used to analyze the topological properties of the 2ATP, including the Localized Orbital Locator (LOL) and Electron Localization Function (ELF). Further attention was drawn to the compound's exceptional pharmacological potential when its ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) characteristics were evaluated. Not to add, molecular docking experiments were carried out to evaluate the feasibility of 2ATP as a bioactive material with possible uses in the pharmaceutical business.

First-principles study of BC3 monolayer for sensing halomethanes: a computer aided investigation

This research used a method called DFT to study how CH3Br, CH3Cl, and CH3F halomethanes stick to boron carbide (BC3) nanosheets, with and without gallium and aluminum doping. Geometric optimisation was conducted for all structures using the B3LYP/6-311 + G (d) method. Furthermore, three different methods were employed to calculate the energy: M06-2X, ωB97X-D3, and CAM-B3LYP/6-311 + G(d). NBO and the QTAIM analysis was conducted to evaluate the WBI, partial natural charge, and donor–acceptor interactions within the molecules. The adsorption energy results showed that adding gallium to BC3 made it best at adsorbing stuff, while BC3 without any additives absorbed the least. However, CH3Cl stuck best to the aluminum-doped BC3 and least to the plain BC3 because it had less energy holding onto it. Also, CH3Br stuck to the nanosheet surfaces the most, while CH3Cl stuck the least. BC3(Ga)NS was discovered to be better at detecting halomethanes than BC3(Al)NS and BC3NS. Also, when the halomethanes were absorbed, the doped nanosheets experienced big changes in their electronic behaviour. The energy gaps for BC3NS, BC3(Al)NS, and BC3(Ga)NS were found to be 3.5%, 15.2%, and 13.6%, respectively. Gallium and aluminum mixed with BC3 seem good for making new sensors to detect halomethanes.

Enhanced removal of tetracycline by vitamin C-modified cow manure biochar in water

Vitamin C (VC), due to its chemical properties, can provide more oxygen-containing functional groups such as hydroxyl groups for biochar (BC), which promotes the adsorption of tetracycline on biochar. Therefore, in this study, cow dung biochar (CDBC) was modified with VC and VC-modified CDBC (CDBC-VC) was synthesized. The modified biochar was characterized and related factors, adsorption kinetics, isotherms and adsorption mechanisms were investigated. Adsorption kinetics indicate a fast rate of adsorption. The adsorption isotherms showed that the maximum adsorption capacity was 31.72 mg/g (CDBC) and 50.90 mg/g (CDBC-VC), respectively, and the adsorption process was inhomogeneous with multiple molecular layers and the adsorbent has a higher affinity. Mechanistic studies showed that hydrogen bonding interactions, π-π electron donor-acceptor interactions, hydrophobic interactions, and electrostatic interactions were the key to the adsorption process. The analysis of adsorbent regeneration showed that CDBC-VC had good adsorption performance. CDBC and CDBC-VC showed the best performance in simulated industrial wastewater with removal rates of 78.81% and 93.69%. The adsorption mechanism was comprehensively analyzed using six machine learning models. The extreme gradient boosting model gave the best fit. Analysis of the weights of the input variables for predicting adsorption efficiency showed that the ratio of initial TC concentration to BC dosage (29.8%), specific surface area (23%), isoelectric point (8.8%), and ash content (7.7%) had a significant effect on the predicted results.

Singlet oxygen generation by nanoassemblies containing porphyrin macrocycles: Steric and screening effects, energy transfer and competing processes

In this semi-review paper, we discuss some principal aspects that should be taken into account upon quantitative analysis of the interaction with molecular oxygen O2 and the singlet oxygen (1O2 or [Formula: see text] generation by various tetrapyrrolic photosensitizers (including monomers, chemical dimers, triads, pentads and organic-inorganic nanoassemblies). In all cases, the direct experimental measurements of 1O2 emission at [Formula: see text] = 1.27 μ need to be corrected to the solvent influence (refractive indexes, molecular polarizability) on the rate constant of the radiative transition [Formula: see text] in a 1O2 molecule. For porphyrin and chlorin chemical dimers, T1 states quenching by O2 followed by 1O2 generation depends on donor-acceptor interactions between the dimer halves, and extra-ligation effects as well as the spacer flexibility. In the case of self-assembled triads and pentads containing Zn-porphyrin dimers and pyridyl substituted porphyrin free bases (H2P) as extra-ligands, quenching rate constants of H2P T1 states by O2 are smaller compared to those found for individual monomeric H2P molecules which is explained by the spatial screening influence of a strongly quenched Zn-porphyrin dimer in multiporphyrin complexes. Finally, at 293 K for nanoassemblies of two types (semiconductor quantum dots CdSe/ZnS + coordinative linked tetra-pyridyl porphyrins, and semiconductor negatively charged quantum dots AgInS/ZnS + positively charged porphyrin molecules) it was quantitatively shown that non-radiative energy transfer FRET quantum dot [Formula: see text] porphyrin (competing with electron tunneling under conditions of quantum confinement) is only responsible for the singlet oxygen 1O2 generation by nanoassemblies.

Molecular-Scale Interactions in the Choline Chloride-Ethylene Glycol Deep Eutectic Solvent System: The Importance of Chromophore Charge in Mediating Rotational Dynamics.

We report on the rotational diffusion dynamics of three chromophores (disodium fluorescein, oxazine 725, and perylene) in a series of choline chloride-ethylene glycol (ChCl:EG) deep eutectic solvent (DES) systems. We observe behavior independent of DES bulk viscosity for the cationic and neutral probes and behavior that is consistent with stick-limit interactions for the modified Debye-Stokes-Einstein model for the anionic probe. This finding indicates that the anionic species is integral to the interactions between DES constituent species that are responsible for local organization, consistent with previous MD simulations that showed higher interaction energies associated with both the hydrogen bond donor (EG) and hydrogen bond acceptor (Ch+) interactions with Cl- in ChCl:EG mixtures. The reorientation data reported here also indicate a region around 15 mol % ChCl where the stoichiometric relationship between the species gives rise to changes in the details of intermolecular interactions.

High‐Efficiency Near‐Infrared Iridium(III) Complexes with Tailored Ligands for Solution‐Processed OLEDs with Maximum EQE of 3.75% at 830 nm

AbstractThe development of highly efficient pure near‐infrared (NIR) emitting organic materials with emission beyond 800 nm is extremely challenging due to the limitation of the energy gap law. Herein, three efficient NIR emitting iridium(III) complexes are developed adopting pyrido[3,4‐b]pyrazine derivatives as the cyclometalated C^N ligands, namely (Epptt)2Iracac (1), (pptt)2Iracac (2), and (ppCz)2Irtmd (3). Due to the enhanced donor–acceptor interaction inside the ligand, the conjugation‐extended and electron‐richer N‐phenylcarbazole unit at the C‐part of the ligands endows complex 3 with a large bathochromic shift of emission peak from 796 to 862 nm in toluene solution, compared with thieno[3,2‐b]thiophene C‐part in complex 2. The solution‐processed OLEDs based on complex 3 achieved a record high maximum external quantum efficiency of 3.75% and low efficiency roll‐off with the emission peak at 830 nm, a champion efficiency in the Ir(III) based OLEDs with emission peak exceeding 800 nm. This work opens a new avenue for the development of high‐efficiency pure NIR organic emitters based on Ir(III) complexes for various applications.

Additive effects of rice husk-based carbon-silica composites on adsorption of diclofenac sodium and carbamazepine from aqueous solutions

The present study investigated the adsorption of diclofenac sodium (DCF) and carbamazepine (CBZ) on carbon-silica composites (CSC), activated carbon (RH-AC) and biogenic silica (RH-BS) based on rice husks from aqueous solutions. The materials were characterised using scanning electron microscopy, infrared spectroscopy, inductively coupled plasma optical emission spectroscopy, nitrogen sorption and elemental analysis. These methods provided essential information on the morphology, chemical composition, textural properties and surface characteristics of porous materials. The results of the adsorption studies demonstrate that the investigated materials exhibit varying adsorption capacities for DCF and CBZ. The maximum adsorption capacity was achieved by CSCs, with 1111 mg g−1 for DCF and 455 mg g−1 for CBZ and indicates additive effects on the adsorption capacity of CSCs compared to RH-AC and RH-BS. In addition to the hydrogen bonds and the π-π electron donor-acceptor interactions of the carbon component, further hydrogen bonds are formed by the silanol groups of the silica component. The CSCs derived from rice husks represent an innovative approach to the more efficient removal of pharmaceutical residues from wastewater. This is accomplished by utilizing a single starting material for both components, thereby yielding a unique structural combination.

Enhancing Donor–Acceptor Interaction and Framework Stability by the Povarov Reaction for Photocatalytic H2O2 Production

Enhancing Donor–Acceptor Interaction and Framework Stability by the Povarov Reaction for Photocatalytic H₂O₂ Production

CRYOCHEMICAL SYNTHESIS OF HYBRID NANOFORMS BASED ON SILVER AND THE ANTIBACTERIAL DRUG SUBSTANCE DIOXIDINE

Hybrid nanoforms based on silver and antibacterial drug dioxidine (2,3-bis-(hydroxymethyl)quinoxaline 1,4-di-N-oxide) were prepared by the method of joint co-condensation of metal and ligand vapors on a liquid nitrogen cooled surface. The samples obtained by low temperature co-condensation were characterized by FTIR-, UV-Vis and XPS-spectroscopy, ТЕМ, SEM and powder X-ray phase analysis (ХРА). It was shown that cryomodified nanoforms preferably consist of anhydrous triclinic (T-phase) crystal phase of dioxidine, the dimensions of dioxidine particles ranges from 50 to 300 nm, the average size of included silver nanoparticles is (15±3) nm. Broadening of the diffraction patterns belonging to silver shows the transition of metallic silver to the nanoscale state. The FTIR results indicate for hybrid nanoforms stabilized by donor-acceptor interactions of surface silver atoms with hydroxyl groups and with donor N-atoms of quinoxaline cycles of dioxidine molecules.

Single crystal XRD, Hirshfeld surface analysis and computational approach for exploration of novel xanthene derivative

In order to study the structure-activity relationship of xanthene compound, hexahydro xanthene derivative was synthesized and characterized by single crystal X-rays diffraction. The molecular geometry was described in terms of dihedral angles between various rings present in structure. The stability of the supramolecular assembly was reinforced by multiple intermolecular interactions, which were inspected comprehensively via Hirshfeld surface analysis. DFT study revealed the excellent electronic properties and reactivity of synthesized compound. FMO is employed to uncover the orbitals energies and charge transfer within compound. The contribution of van der Waals forces is minor, while covalent nature of bonding is evidenced by the quantum theory of atoms in molecules (QTAIM) study. The electron transition from nonbonding orbitals (LP) to antibonding (LP*) are most prominent donor-acceptor interactions with significant stabilization energy. Ab-initio molecular dynamics reveals the kinetic and thermodynamic stability of present compound at room temperature. The excellent nonlinear optical properties and reactivity is revealed by its remarkable hyperpolarizability value.

Spatial Structure of Electron Interactions in High-entropy Oxide Nanoparticles for Active Electrocatalysis of Carbon Dioxide Reduction.

High-entropy oxides (HEOs) exhibit distinctive catalytic properties owing to their diverse elemental compositions, garnering considerable attention across various applications. However, the preparation of HEO nanoparticles with different spatial structures remains challenging due to their inherent structural instability. Herein, ultrasmall high-entropy oxide nanoparticles (less than 5nm) with different spatial structures are synthesized on carbon supports via the rapid thermal shock treatment. The low-symmetry HEO, BiSbInCdSn-O4, demonstrates exceptional performance for electrocatalytic carbon dioxide reaction (eCO2RR), including a lower overpotential, high Faraday efficiency across a wide electrochemical range (-0.3 to -1.6V), and sustained stability for over100h. In the membrane electrode assembly electrolyzer, BiSbInCdSn-O4 achieves a current density of 350mAcm-2 while maintaining good stability for 24h. Both experimental observations and theoretical calculations reveal that the electron donor-acceptor interactions between bismuth and indium sites in BiSbInCdSn-O4 enable the electron delocalization to facilitate the efficient adsorption of CO2 and hydrogenation reactions. Thus, the energy barrier of the rate-determining step is reduced to enhance the electrocatalytic activity and stability. This study elucidates that the spatial structure of metal sites in HEOs is able to regulate CO2 adsorption status for eCO2RR, paving the way for the rational design of efficient HEO catalysts.

Interstitial Optical Fiber-Mediated Multimodal Phototheranostics Based on an Aggregation-Induced NIR-II Emission Luminogen for Orthotopic Breast Cancer Treatment.

One-for-all phototheranostics based on a single molecule is recognized as a convenient approach for cancer treatment, whose efficacy relies on precise lesion localization through multimodal imaging, coupled with the efficient exertion of phototherapy. To unleash the full potential of phototheranostics, advancement in both phototheranostic agents and light delivery methods is essential. Herein, an integrated strategy combining a versatile molecule featuring aggregation-induced emission, namely tBuTTBD, with a modified optical fiber to realize comprehensive tumor diagnosis and "inside-out" irradiation in the orthotopic breast tumor, is proposed for the first time. Attributed to the intense donor-acceptor interaction, highly distorted conformation, abundant molecular rotors, and loose intermolecular packing upon aggregation, tBuTTBD can synchronously undergo second near-infrared (NIR-II) fluorescence emission, photothermal and photodynamic generation under laser irradiation, contributing to a trimodal NIR-II fluorescence-photoacoustic (PA)-photothermal imaging-guided phototherapy. The tumor treatment is further carried out following the insertion of a modified optical fiber, which is fabricated by splicing a flat-end fiber with an air-core fiber. This configuration aims to enable effective in situ phototherapy by maximizing energy utilization for therapeutic benefits. This work not only enriches the palette of NIR-II phototheranostic agents but also provides valuable insight for exploring an integrated phototheranostic protocol for practical cancer treatment.

π-Bridge Regulates Donor–Acceptor Interactions for Long-Wavelength Photoacoustic Imaging and Enhanced Photothermal Therapy

π-Bridge Regulates Donor–Acceptor Interactions for Long-Wavelength Photoacoustic Imaging and Enhanced Photothermal Therapy

Open-cage metallo-azafullerenes as efficient single-atom catalysts toward oxygen reduction reaction.

Very recently, open-cage metallo-azafullerenes PbC100N4H4 and Pb2C100N4H4 containing one Pb-N4-C moiety have been synthesized via the electron beam. Herein, we utilized density functional theory calculations in combination with abinitio molecular dynamics (AIMD) simulations to study the geometric and electronic structures, bonding properties, thermodynamic stability, and catalytic performance of MC100N4H4 and M2C100N4H4 (M = Ge, Sn, Pb). Metal-nitrogen distances and metal-metal distances increase along with the metal radius while the metal atom is positively charged. Energy decomposition analysis revealed that the bonding interactions between M and the C100N4H4 fragment could be described as the donor-acceptor interaction between M(ns0(n-1)d10np4) and C100N4H4 fragment, in which the orbital interactions terms contribute more than the electrostatic interactions. AIMD simulations demonstrate that those metallo-azafullerenes exhibit thermodynamic stability at room temperature. These metallo-azafullerenes, which could serve as typical carbon-supported single-atom catalysts, possess enhanced catalytic performance toward the oxygen reduction reaction (ORR) compared to the planar catalysts, which is attributed to the curvature of metallo-azafullerenes. GeC100N4H4 and SnC100N4H4 exhibit high catalytic performance in the 4e-ORR pathway to H2O, whereas only PbC100N4H4 is suitable for the 2e-ORR reaction pathway because of the difficulty in obtaining electrons. All M2C100N4H4 favors the 4e-reaction pathway due to the presence of the axial metal atom. Our finding of open-cage metallo-azafullerenes as efficient single-atom catalysts holds profound implications for both fundamental research in catalysis and practical applications in fuel cells and other electrochemical devices.

Mechanochromism and aggregation-induced emission in a fluorene-fumaronitrile-based molecular system: The influence of supramolecular control on donor-acceptor interactions

Effective control and reversible switching of solid-state luminescence in organic molecules are crucial for optoelectronic applications. This study presents a novel molecular system based on fluorene-diphenylfumaronitrile-fluorene (FDF), which exhibits mechanochromism and aggregation-induced emission (AIE). The design utilizes fluorene as the donor, leveraging its high photoluminescent quantum yield, thermal stability, and optimal solubility. The diphenylfumaronitrile moiety, used as the acceptor, is characterized by antiparallel dipoles, which align orthogonally with the chromophore's long axis, promoting effective self-assembly and supramolecular control of interchromophore interactions, in association with the cooperative hydrogen bonding of the amide end-functional groups. FDF demonstrates significant mechanochromic properties, in which mechanical stress induces a reversible shift from greenish-yellow to red emission due to alterations in molecular packing and hydrogen bonding. Additionally, FDF exhibits pronounced AIE behavior in DMF/water mixtures, transitioning from non-emissive in DMF to highly fluorescent upon nanoparticle formation. The investigation reveals that the control over donor-acceptor interactions is critical in modulating these luminescent properties, offering potential applications in stress sensing, bioimaging, and optoelectronic devices. These findings provide deeper insights into the molecular mechanisms underlying mechanochromism and AIE, highlighting the dual-functional nature of FDF and its applicability in advanced materials sciences.

Calcium oxide adsorption of gas phase PCDD/Fs and its impact on the adsorption properties of activated carbon

Calcium oxide (CaO), utilized in semi-dry/dry desulfurization systems at municipal solid waste incineration (MSWI) plants, demonstrates some capability to remove polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). This study assessed the gas-phase PCDD/F removal performance of CaO, activated carbon (AC) and CaO-AC mixtures. Alone, CaO achieved removal efficiencies of only 31.9% for mass and 50.8% for I-TEQ concentration. However, CaO-AC mixtures exhibited significantly higher efficiencies, reaching 96.0% and 92.5% for mass and I-TEQ concentrations, respectively, surpassing those of AC alone, which were 74.7% and 58.5%. BET analysis indicated that CaO's limited surface area and pore structure are major constraints on its adsorption performance. Density functional theory (DFT) calculations revealed that the π-π electron donor-acceptor (EDA) interaction enhances the adsorption between AC and PCDD/F, with adsorption energies ranging from −1.02 to −1.24 eV. Additionally, the induced dipole interactions between CaO and PCDD/F contribute to adsorption energies ranging from −1.13 to −1.43 eV. Moreover, with increasing chlorination levels, PCDD/F molecules are more predisposed to accept electron transfers from the surfaces of AC or CaO, thereby facilitating adsorption. The calculation for mixed AC and CaO showed that CaO modifies AC's properties, enhancing its ability to adsorb gas phase PCDD/Fs, with the higher adsorption energy and more electrons transfer, aligning with gas phase PCDD/Fs adsorption experiments. This study provides a comprehensive understanding of how CaO influences the PCDD/F adsorption performance of AC.

Cooperativity in Molecular Recognition of Porphyrin Clefts

The electron-rich cleft cavities of porphyrin-based molecular tweezers encapsulate various electron-deficient guest molecules via π-π stacking and donor-acceptor interactions. In this presentation, we will describe negative cooperativity in the molecular recognition of a trisporphyrin host molecule possessing two cleft cavities. A 1:2 host-guest complexation of the trisporphyrin host with various electron-deficient guest molecules showed strong negative cooperativity. The quantitative discussion of the negative cooperativity was provided by a detailed analysis using isothermal titration calorimetry.1) Hisano, N.; Kodama, T.; Haino, T., Chem. Eur. J. 2023, 29, e2023001072) Hisano, N.; Haino, T., J. Org. Chem. 2022, 87, 4001-4009. Figure 1