Effect Of Substituent Groups Research Articles

Bidirectional "Win-Win": Asymmetrical Nanobowl-Coupled Aggregation-Induced Emissive Nanosilicon-Enhanced Immunochromatographic Strips for the Ultrasensitive Detection of Salmonella typhimurium.

The lack of nanoprobes with an efficient signal response and overlook of cooperation between nanoprobes can be responsible for the unsatisfactory analytical performance of immunochromatographic strips (ITSs). Herein, asymmetrical nanobowl-confined innumerable gold nanoparticles (AuNPs) (AuNPs@AFRNBs) to enhance the light absorption are developed for quenching the fluorescence of aggregation-induced emissive (AIE) nanosilicons, which is used for the construction of a bidirectional complementary-enhanced ITS (BC-ITS) to ultrasensitively detect Salmonella typhimurium (S. typhimurium). Briefly, density functional theory-screened AIEgens with highly fluorescent brightness are confined in nanosilicons, and the nanoconfinement has improved the fluorescent brightness by 6.78-fold compared to the free AIEgens. Moreover, the substituent group effect has also enhanced the fluorescence of the prepared fluorescent nanosilicon by 10,000-fold in ITSs. By virtue of the superior light absorption of AuNPs@AFRNBs, the BC-ITS exhibits a bidirectional "win-win" performance for the sensitive monitoring of S. typhimurium: a "turn-on" mode with a high-brightness colorimetric response and an inverse "turn-off" fluorescence response, whose limits of detection are 364 and 302 CFU mL-1, respectively, which is approximately 100-fold more sensitive than the traditional AuNPs-ITS. Furthermore, the BC-ITS can be successfully used to identify S. typhimurium in milk, illustrating the superiority of the developed BC-ITS in point-of-care diagnosis.

Exploring the Potential of Triphenylmethane-Based Polymers Prepared via Facile Friedel–Craft (F–C) Hydroxyalkylation Polymerization as Gas Separation Membranes: Effect of Substituent Group

Exploring the Potential of Triphenylmethane-Based Polymers Prepared via Facile Friedel–Craft (F–C) Hydroxyalkylation Polymerization as Gas Separation Membranes: Effect of Substituent Group

Antibacterial potentials and DNA study of cobalt(II) complexes containing aminophenol Schiff base moiety

The present study was carried out to investigate the effect of substituent groups on the antibacterial activities of 2-aminophenol Schiff bases and their cobalt (II) complexes. Development of new compounds with potential effects against pathogenic organisms has become necessary due to the increase in microbial resistance reported for existing antiseptics and disinfectants. In line with this, new cobalt (II) complexes with Schiff bases derived from 2-aminophenol and p-substituted benzaldehydes were synthesized. The compounds were characterized using elemental analysis, mass spectrometry, atomic absorption spectroscopy, electrospray ionization mass spectrometry, infrared spectroscopy, 1H NMR and electronic absorption spectroscopy. Results indicate that all metal complexes had a 1:2 metal ligand ratio with magnetic moments characteristic of tetrahedral geometry around the metal ion. The Schiff bases and their metal complexes were screened for in-vitro antibacterial activities against 6 human pathogenic bacteria usually found around the hospitals and homes; Escherichia coli (ATCC 8739), Staphylococcus aureus (ATCC 6538), Pseudomonas aeruginosa (ATCC 19582), Bacillus cereus (10702), Enterococcus faecalis (ATCC 29212) and Kribsella pneumonia (ATCC 10031) with ampicillin used as the reference compound. DNA binding study using calf thymus DNA revealed intercalative mode of activity. The result showed that Schiff bases exhibited moderate inhibitory activity against the tested microorganisms while Schiff base metal complexes exhibited higher antibacterial activity when compared to ampicillin. Our results indicate that these complexes can be employed as active ingredients in development of broad-spectrum antibacterial agents.

Effect of different substituted groups on excited state intramolecular proton transfer of BOHMB

AbstractThe photophysical features of 3‐(benzo[d]oxazol‐2‐yl)‐2‐hydroxy‐5‐methoxy benzaldehyde (BOHMB) were investigated through experimental (J. Phys. Chem. A 2019, 123, 10,246–10,253) and theoretical (Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2022, 266, 120,406) methods. However, the effect of substituent groups on the excited state proton transfer process has not been studied. In this work, the excited state intramolecular proton transfer (ESIPT) dynamics and photophysical properties of BOHMB with different substituent groups were investigated by density‐functional theory (DFT) and time‐dependent DFT (TDDFT) methods at CAM‐B3LYP/6‐311G(d,p) level. The primary parameters related to hydrogen bonding and infrared vibration frequency were obtained to understand the ESIPT properties of BOHMB derivatives. The results indicate that the excited‐state intramolecular hydrogen bond (ESIHB) strengthening behaviors, and the intramolecular hydrogen bond O1–H2···O3 for 1a in the S1 state is the strongest among BOHMB derivatives. From the calculated potential energy curves, it can be inferred that the substitution and position of NH2 and NO2 groups will regulate the excited‐state energy barrier and thus affect the ESIPT process. The molecular absorption peak and fluorescence peak are affected by different substituting groups and different positions.

Retraction Note to: Effects of Substituent Groups on the Crystal Structures and Anti-Cervical Cancer Activity of Zero-/Two-Dimensional Cu(II) Complexes

Retraction Note to: Effects of Substituent Groups on the Crystal Structures and Anti-Cervical Cancer Activity of Zero-/Two-Dimensional Cu(II) Complexes

Electronic Structure Variations of Cu‐Based Water Oxidation Catalysts Bearing Redox‐Active Ligands

AbstractThe physical and electrochemical properties of a series of Cu complexes bearing redox‐active ligands were investigated. The effect of the geometry and electronic structure on the redox potentials of the CuI/II and ligand‐based oxidation was investigated, in both MeCN and aqueous solutions. Here we found that the formation of a delocalized ligand radical is essential to obtain catalytic activity for water oxidation. Furthermore, we found that ligand‐based oxidation can be controlled by electronic effects of substituent methoxy groups on various positions on the ligand. This allows us to propose design principles for ligands employed in water oxidation catalysts that operate via a SET‐HA mechanism: 1) The redox‐active ligand should contain a negative charge of at least −1 or have the ability to oxidize the ligand via PCET whereby a proton is removed from the ligand. 2) The oxidation potential of the redox‐active ligands can be controlled by introduction of substituents. To decrease this potential, the electron density should be directed at the position of the ligand where oxidation occurs. 3) Stabilization of the oxidized ligand by electronic or delocalization effects decreases the oxidation potential.

Ligand-Mediated Regulation of the Chemical/Thermal Stability and Catalytic Performance of Isostructural Cobalt(II) Coordination Polymers.

Regulating the chemical/thermal stability and catalytic activity of coordination polymers (CPs) to achieve high catalytic performance is topical and challenging. The CPs are competent in promoting oxidative cross-coupling, yet they have not received substantial attention. Here, the ligand effect of the secondary ligand of CPs for oxidative cross-coupling reactions was investigated. Specifically, four new isostructural CPs [Co(Fbtx)1.5(4-R-1,2-BDC)]n (denoted as Co-CP-R, Fbtx = 1,4-bis(1,2,4-triazole-1-ylmethyl)-2,3,5,6-tetrafluorobenzene, 4-R-1,2-BDC = 4-R-1,2-benzenedicarboxylate, R = F, Cl, Br, CF3) were prepared. It was found that in the reactions of oxidative amination of benzoxazoles with secondary amines and the oxidative coupling of styrenes with benzaldehydes, both the chemical and thermal stabilities of the four Co-CPs with the R group followed the trend of -CF3 > -Br > -Cl > -F. Density functional theory (DFT) calculations suggested that the difference in reactivity may be ascribed to the effect of substituent groups on the electron transition energy of the cobalt(II) center of these Co-CPs. These findings highlight the secondary ligand effect in regulating the stability and catalytic performance of coordination networks.

Electronic effect of substituent groups on the oxidation and reduction of bis(2,2′:6′,2″-terpyridine)ruthenium

A series of bis(tpy)ruthenium(II) (tpy = differently substituted 2,2′:6′,2″-terpyridine) were prepared. The substituents were chosen to range from electron donating (pyrrolidinyl, hydroxy, tert-butyl, methoxy, phenyl) to electron withdrawing (Cl, Br). Electrochemistry results show that the complex with the most electron donating group in the series, [Ru(4′-(N-pyrrolidinyl)-2,2′:6′,2″-terpyridine)2]2+, oxidizes at 0.363 V vs the redox couple of ferrocene (Fc/Fc+). The oxidation of [Ru(4′-chloro-2,2′:6′,2″-terpyridine)2]2+, containing the electron withdrawing chlorine group, is much higher, 0.992 V vs Fc/Fc+. Theoretical density functional theory calculations confirmed that the oxidation and reduction of bis(tpy)ruthenium(II) are metal and ligand based, respectively. Graphs comparing the experimentally measured redox potentials and theoretically calculated energies, charges, potentials and various global and local reactivity parameters, all show linear relationships associated with the donating/withdrawing nature of the substituents as quantified by Hammett constants. All these relationships may be utilized to quantify the electronic influence of substituent groups on the redox chemistry of bis(tpy)ruthenium(II) complexes. Linear relationships obtained may also be utilized in the design of bis(tpy)ruthenium(II) type of molecules with a required oxidation or reduction potential. DFT calculations also indicate the potential utilization of these complexes as dye sensitizers in dye-sensitized solar cells.

Unraveling the substituent group effects on the emission properties of fluorenone derivatives

Elucidating the structure–property relationship is vital for developing organic luminescent materials with excellent properties and performance optimization. Herein, we designed and synthesized three types of fluorenone-based molecules named FO-Ph, FO-Na and FO-An, with similar structures but different sizes of substituent groups (benzene, naphthalene and anthracene). This slight modification resulted in significantly different optical properties of luminogens in dilute solutions and powders. FO-Ph as an aggregation-caused quenching (ACQ) emitter displayed strong emissions in solution; moreover, after the addition of a poor solution, the fluorescence intensity of FO-Ph gradually decreased. On the contrary, FO-Na displayed aggregation-induced emission enhancement properties, and FO-An was non-emissive in solutions but displayed enhanced emission owing to its molecular aggregation, indicating that FO-An comprises an AIE-active molecule. The characterization of the photophysical properties, theoretical calculations and an X-ray single crystal analysis showed that the emission properties of the three compounds could be affected by the size of substituent groups, twisted geometry and molecular packing modes. The three fluorenone luminogens exhibited different force-induced emission enhancement properties. Moreover, FO-Ph can be used as a water detector and showing high sensitivity. This study elucidates the AIE and ACQ phenomena of fluorenone complexes and provides effective ways for developing organic luminescent materials.

The effect of substituent group in allyl benzoxazine on the thermal, mechanical and dielectric properties of modified bismaleimide

Allyl benzoxazine resin (BOZ-A) synthesized from 2,2′-diallyl bisphenol A (DABPA), aniline and paraformaldehyde has been used to improve the mechanical and processing properties of bismaleimide resin. However, the lower heat resistance and the unsatisfactory dielectric properties cannot satisfy the requirements of high-performance composites in aerospace fields. Introducing nonpolar materials into the resin matrix effectively improves the dielectric properties. Inspired by the designability of benzoxazine, a novel allyl benzoxazine resin grafted with trifluoromethyl (BOZ-F) or methyl (BOZ-C) was synthesized and blended with BD-type bismaleimide resin (BDM-C and BDM-F) to explore the effect of substituent groups on the comprehensive performance. Due to the different electronic effects of the substituents, BDM-C possesses higher reactivity with a polymerization temperature of 212.7 °C, which is lower than that of BDM-A (217.8 °C) and BDM-F (226.6 °C). Their respective reactivity also leads to differences in rheological properties. Specifically, BDM-F exhibited the excellent thermal stability with a Tg of 308.3 °C, which is 17.2 °C higher than that of BDM-A. Furthermore, the dielectric constant (Dk) and dielectric loss (Df) of BDM-F at 10.5 GHz decreased to 3.06 and 0.0078 from 3.13 and 0.0114 when compared with BDM-A. In addition, BDM-C demonstrated the highest bending strength of 136.02 MPa. The current study delivers an effective approach to balance the performance of thermosetting resins by regulating substituents, which is valuable for potential application in wave-transparent fields.

Effect of Substituent Groups on the Strength of Intramolecular Hydrogen Bonds in 2,4-Dihydroxybenzophenone UV Absorbers

2,4-Dihydroxybenzophenone is the most widely used molecule in the benzophenone group of UV absorbers. It is known that the UV absorption ability is dependent on the substituents. Numerous studies have shown that the strength of intramolecular hydrogen bonds is the main factor affecting this type of UV absorber. However, the effect of substituents on the formation and nature of the hydrogen bonds has not been well studied. In this work, the effect of the type of substituent and the substitution position on the absorption intensity of 2,4-dihydroxybenzophenone molecules is verified both experimentally and theoretically. The effect of substituents on the intramolecular hydrogen bonding of 2,4-dihydroxybenzophenone was investigated by DFT calculations. The results indicate that the addition of different substituents leads to various changes in the strength of the hydrogen bonding in 2,4-dihydroxybenzophenone. On the X-substitution site or the Y-substitution site, halogen groups and electron-absorbing groups such as -CN and -NO2 increase the strength of the hydrogen bond, while electron-giving groups such as -N(CH3)2 and -OCH3 decrease the strength of the bond. For the same substituent, the one at the Y site has a higher effect on hydrogen bonding than that at the X site. By NBO analysis, it was found that the substituents would cause charge redistribution of the individual atoms of 2,4-dihydroxybenzophenones, thus affecting the formation and strength of the hydrogen bonds. Moreover, when the substituent is at the Y substitution site, the oxygen atom of the carbonyl group is less able to absorb electrons and more charge is attracted to the oxygen atom of the hydroxyl group, resulting in a larger charge difference between the two oxygen atoms and an increase of bond energy. Finally, a multiple linear regression analysis of the NPA charge number of the atoms involved in the formation of the hydrogen-bonded chelated six-membered ring was performed with the energy of the hydrogen bond and the percentage of influencing factors estimated, which were found to jointly affect the strength of hydrogen bonding. The aim of this study is to provide theoretical guidance for the design of benzophenone-based UV absorbers that absorb UV light of specific wavelength bands.

Corrosion Inhibition Properties of Lawsone Derivatives againts Mild Steel: A Theoretical Study

Theoretical studies have been carried out using DFT, ab initio MP2 and Monte Carlo (MC) simulations of corrosion inhibitors from lawsone derivatives against carbon steel. The research focuses on studying the effect of substituent groups in the lawsone structure on the efficiency of corrosion inhibition in mild steel. Quantum chemical parameters of lawstone inhibitors in neutral and protonated conditions have been calculated. Fukui’s function analysis predicts that the active side of the inhibitor will be adsorbed on the mild steel surface. MC simulation is used to understand the adsorption patterns of lawsone compounds on metal surfaces. The organic inhibitor L-NH2 has better performance as a corrosion inhibitor for mild steel in neutral or protonated conditions.

Dissociation Constant Studies of 2-Substituted 4-Formylbenzoic Acid based on Conductometric Parameters using Fuoss-Hsia Theories

The dissociation constant is a quantitative measure of the strength of an acid in solution. This study examines dissociation constant for the series substituted acids like Ortho-alkoxy-4-formylbenzoic acid. The use of (2-methoxy ethanol) as a solvent contributed to the study expected to form free ions or solvent separated ion pair which has been studied with the use conductometric method at different temperatures ranged from 293.15 to 318.15K. The study aims at figuring out dissociation constant, equivalent conductance at infinity dilution, and Walden product by minimization technique using Fuoss-Hsia for both (Modified and Complete) equations. It has been found in the results that the calculated values based on statistical sum square (different between practical and theoretical values) is equivalent conductance at infinity dilution and dissociation constant. It has also been observed that increase the temperature leads to the increase of the molar conductance at infinity dilution, and the increase in association. Moreover, the substituted alkoxy group also affected dissociation of compounds. In this study, the thermodynamic parameters (Ho, Go and So) have also been evaluated and discussed. Finally, the effect of substituent groups on rate of dissociation was studied and explained with agreement to the principles of mesomeric(M) and Inductive effect(I) of substituent groups on dissociation constant.

Cardo polyimides with high Tg and transparency derived from bisphenol fluorenes and 1,4-bis(4-fluorophthalimide)cyclohexanes via aromatic nucleophilic substitution

Two series of transparent cardo polyimides (PIs) derived from bisphenol fluorenes and 1,4-bis(4-fluorophthalimide)cyclohexanes (BFCH) with different ratios of trans- and cis-1,4-diaminocyclohexane were prepared via aromatic nucleophilic substitution. These PIs exhibited high glass transition temperatures (Tgs) of 271–352 °C, 5% weight loss temperatures (Td5%) of 400–433 °C in nitrogen, mechanical properties of tensile strengths of 62–107 MPa, tensile moduli of 3.0–4.4 GPa and elongations at break of 1.7–4.5% and great solubility in a variety of organic solvents. These PI films appeared excellent optical transparency, which displayed the cut-off wavelengths from 323 to 355 nm and high transmittance at 450 nm with more than 85 %. The steric effects of different substituent groups on bisphenol fluorene and different ratios of trans/cis configuration were also investigated.

From isostructural to hetero-structural one-dimensional coordination polymers adjusted by changing the ligand substituent group from pyrazine to furan

A new ligand, 4-(4-carboxyphenyl)-6-(pyrazin-2-yl)picolinic acid (H2L1), was used to construct four isostructural one-dimensional (1 D) zig-zag chain coordination polymers ([M(L1)(H2O)2]·3H2O, M = Mn (1), Co (2), Cd (3) and Zn (4)). Moreover, when changing the ligand substituent group from pyrazine ring to furan ring, another new ligand, 4-(4-carboxyphenyl)-6-(furan-2-yl)picolinic acid (H2L2), was synthesized. Based on H2L2, different structural 1 D coordination polymers, ([Mn(L2)(H2O)2] (5) and [Ni(L2)(H2O)2]·H2O (6)), have been obtained under the same solvothermal conditions as for the syntheses of isostructural 1–4. Interestingly, only through changing the ligand substituent group, the 1 D isostructural zig-zag chain (1–4) was adjusted to a 1 D molecular box chain (5) and 1 D linear chain (6), which should be ascribed to ligand substituent group effects. The various 1 D chain structures originate from the types of ligand substituent group: the substituent group with a pyrazine ring only yields isostructural coordination polymers 1–4, whereas the substituent group with a furan ring can construct different structural coordination polymers, such as a 1 D molecular box chain (5) or a 1 D linear chain (6). The photoluminescent properties of all coordination polymers were also examined.

Concerted effects of substituents in the reaction of [rad]OH with 2-, 3-, and 4-hydroxybiphenyls

Studies on the distribution of products in radiolytic hydroxylation of hydroxybiphenyls (HBPs) to obtain information on the concerted effect of substituent groups at the OH addition site have been conducted. Liquid chromatography was used to analyze the radiolytic products. Results show that OH is selectively added to the free positions of aromatic rings and the directing effect of the substituents was –OH > phenol > phenyl. The yields of each product are provided; these reflect the charge distribution in the HBP, such that the phenyl ring modified the ortho-para directing effect of the –OH substituent. The ratio of addition of the OH to the HBPs obtained provide a quantitative basis for considering the effect of substituents in determining the site of OH attack on these compounds and provides additional valuable data on the attack of the OH for studies on the degradation of aromatic compounds present in polluted waters.

Benzenesulfonamides Incorporating Hydantoin Moieties Effectively Inhibit Eukaryoticand Human Carbonic Anhydrases.

A series of novel 1-(4-benzenesulfonamide)-3-alkyl/benzyl-hydantoin derivatives were synthesized and evaluated for the inhibition of eukaryotic and human carbonic anhydrases (CAs, EC 4.2.1.1). The prepared compounds were screened for their hCA inhibitory activities against three cytosolic isoforms as well as two β-CAs from fungal pathogens. The best inhibition was observed against hCA II and VII as well as Candida glabrata enzyme CgNce103. hCA I and Malassezia globosa MgCA enzymes were, on the other hand, less effectively inhibited by these compounds. The inhibitory potency of these compounds against CAs was found to be dependent on the electronic and steric effects of substituent groups on the N3-position of the hydantoin ring, which included alkyl, alkenyl and substituted benzyl moieties. The interesting results against CgNce103 make the compounds of interest for investigations in vivo as potential antifungals.

Effect of hydroxyl group on foam features of hydroxyl-based anionic ionic liquid surfactant: Experimental and theoretical studies

Ionic liquid surfactant (ILS) shows potential application in surfactant enhancing oil recovery (SEOR). The structure–activity relationship between structural characteristics and foam feature is significant for the design and selection of favorable ILS for foam enhanced oil recovery (FEOR). In this paper, the effect of structural substituent groups of anionic ILSs on foam features was established through experimental methods and Density functional theory (DFT) simulations. Physicochemical features of hydroxyl-based anionic ILS, 1-(2,3-dihydroxypropyl)-3-butylimidazolium dodecyl sulfate ([DPbim][DS]) was detected. By surface tensiometry, the critical micelle concentration (CMC) value of [DPbim][DS] was 0.427 mmol/L. Foam properties of three ILSs ([DPbim][DS], [Hmim][DS] (1-hexyl-3-methylimidazolium dodecyl sulfate), and [Bmim][DS] (1-butyl-3- methylimidazolium dodecyl sulfate), and sodium dodecyl sulfate (SDS) were established. The foam features of ILSs and SDS followed: [DPbim][DS] > [Hmim][DS] > [Bmim][DS] > SDS. ILS hydrates showed tendency: [Bmim][DS](H2O)n > [Hmim][DS](H2O)n > [DPbim][DS](H2O)n. D0 values followed the tendency: [DPbim][DS](H2O)n > [Hmim][DS](H2O)n > [Bmim][DS](H2O)n. Experimental and DFT results verified the introduction of hydroxyl group and longer alkyl chain length in imidazolium cation was favorable for foam features of ILSs. This information will help to screen new foam surfactants for FEOR.

The substituent group effect: investigation of naphthalimide-spermidine conjugates binding to DNA by spectroscopy, molecular docking and dynamics

• The interaction of Naphthalimide-polyamine conjugates binding to DNA was studied by spectroscopy, molecular docking and dynamics. • Naphthalimide-polyamine conjugates binding to DNA by intercalation and groove into herring sperm DNA. • There was a substituted group effect in the course of DNA interaction with substituted naphthalide-polyamine conjugates. • Naphthalide-polyamine conjugates could cause the little conformation change of DNA. The investigation of mononaphthalimide spermidine conjugates ( 1∼4 ) binding to herring sperm DNA was performed by UV/vis absorption and fluorescent spectra under physiological conditions (pH=7.4). The molecular docking and dynamics were also applied to analyze the interactive mode and molecular dynamic property of their binding to DNA. The observed different spectral change of compounds 1∼4 binding to DNA and the replacement of EB from DNA-EB complexes by compounds showed that these compounds could bind to DNA in patterns of intercalation and groove binding. The further fluorescent variable temperature tests revealed that the quenching mechanism of compounds 1∼4 binding to DNA was belonged to a static one. The quenching constants, binding constants and thermodynamic parameters indicated that the binding force of the compounds-DNA was closely related to the substituent on the aromatic rings of the compounds. Besides, the forces between DNA and compounds were mainly hydrogen bond and hydrophobic force. The results of circular dichroism showed that the compounds caused insignificant conformational change of B-A type DNA, indicating these compounds were not classical DNA intercalating agents. Molecular docking and potassium iodide experiments on the fluorescence of the compound-DNA complex also supported their interactive modes and the substituent effects. The substituent effects in the compound-DNA complexes were further appraised by molecular dynamics, which resulted in the different values of root-mean-square deviation (RMSD) and root-mean-square fluctuation (RMSF). The values of RMSD and RMSF of different compound-DNA complexes indicated that compounds 1∼4 could induce the slightly conformational change of DNA, which were similar to that of compound 5 .

Redox Chemistry of tris(β-diketonate)cobalt(III) Complexes: A Molecular View

Reduction of low spin S = 0 tris(β-diketonate)cobalt(III) complexes leads to an intermediate spin S = 3/2 anion. This electron rearrangement upon reduction could be the reason why a large peak potential difference between the reduction and re-oxidation peaks was observed during electrochemical analysis, using cyclic voltammetry. It is shown that experimental redox potentials obtained from the following methods, namely (i) polarography, (ii) cyclic voltammetry on a hanging Hg electrode, as well as (iii) cyclic voltammetry on a carbon fibre surface, related linearly to various empirical (Gordy scale group electronegativities, Hammett meta-substituent constants, pK a and the Lever electronic parameters) and density functional theory (DFT) calculated (LUMO energy, adiabatic electron affinity, chemical potential, global electrophilicity index and molecular electrostatic potential on Co) reactivity parameters. Deviations from these linear trends were due to a resonance effect of aromatic substituent groups. The linear relationships obtained for complexes containing aliphatic substituent groups can be used to predict redox potential and the electrophilic reactivity of related tris(β-diketonate)cobalt(III) complexes.