Excited State Dipole Moments Research Articles

Assessing intra- and inter-molecular charge transfer excitations in non-fullerene acceptors using electroabsorption spectroscopy

Organic photovoltaic cells using Y6 non-fullerene acceptors have recently achieved high efficiency, and it was suggested to be attributed to the charge-transfer (CT) nature of the excitations in Y6 aggregates. Here, by combining electroabsorption spectroscopy measurements and electronic-structure calculations, we find that the charge-transfer character already exists in isolated Y6 molecules but is strongly increased when there is molecular aggregation. Surprisingly, it is found that the large enhanced charge transfer in clustered Y6 molecules is not due to an increase in excited-state dipole moment, Δμ, as observed in other organic systems, but due to a reduced polarizability change, Δp. It is proposed that such a strong charge-transfer character is promoted by the stabilization of the charge-transfer energy upon aggregation, as deduced from density functional theory and four-state model calculations. This work provides insight into the correlation between molecular electronic properties and charge-transfer characteristics in organic electronic materials.

Excited state dipole moments of two dicyanobenzene isomers from thermochromic shifts and ab initio calculations

The excited state dipole moments of two positional isomers of dicyanobenzene have been determined from thermochromic shifts of the absorption and fluorescence emission spectra in ethyl acetate solution and compared to the results of ab initio calculations. We found that the dipole moments of excited states from thermochromic shifts closely resemble the ab initio values of the isolated molecule, while the results of conductor-like screening model (COSMO) using the same wave function model as for the isolated molecule, shows considerable deviations from the experimental values. It is shown that the dipole moments of the two cyano groups add up vectorially for both the ground and excited states.

Synthesis, Photophysical, and AIE Properties of 2H-Imidazole-Derived Push-Pull Fluorophores

AbstractA four-stage method for the synthesis of 2H-imidazole-derived push-pull fluorophores was developed. The synthesized compounds are characterized by absorption in the range of 250–400 nm, emission of up to 617 nm, and quantum yields of up to 99%. Compounds bearing a tetraphenylethylene fragment demonstrated the AIE effect in a solution with a water fraction fw >90% and significant increase in the emission intensity of up to 20 times and quantum yields of up to 22%. The ICT states for these fluorophores were confirmed by calculating the excited state dipole moments (>23D). The reported synthetic method enables fine-tuning of the fluorescent properties for the developed photoactive molecular systems by varying donor fragments. The obtained compounds could be of particular interest in the design of photoactive organic and hybrid materials.

Temperature effect on spectral characters and dipole moment in short-lived excited singlet S1 state of 3HBI-7D-2HChromen-2-one laser dye in non-associative and highly viscous glycerol solvent

Steady state method is employed to study the effect of temperature on the absorption and emission characteristics of 3-(1H-benzo[d]imidazol-2-yl)-7-(diethylamino)-2H-chromen-2-one(3HBI-7D-2HChromen-2-one) laser dye in glycerol solvent. Temperature induces thermal effect on maxima absorption, emission wavelength, fluorescence intensity etc. Radiative and non-radiative transition probabilities mechanism, fluorescence lifetime, frequency assisted parameters decay rate constants, and activation energy is estimated. Advance thermochromic shift method is adopted to determine the ground and excited state dipole moments.

Toward Accurate Two-Photon Absorption Spectrum Simulations: Exploring the Landscape beyond the Generalized Gradient Approximation.

In this Letter, we present a pioneering analysis of the density functional approximations (DFAs) beyond the generalized gradient approximation (GGA) for predicting two-photon absorption (2PA) strengths of a set of push-pull π-conjugated molecules. In more detail, we have employed a variety of meta-generalized gradient approximation (meta-GGA) functionals, including SCAN, MN15, and M06-2X, to assess their accuracy in describing the 2PA properties of a chosen set of 48 organic molecules. Analytic quadratic response theory is employed for these functionals, and their performance is compared against the previously studied DFAs and reference data obtained at the coupled-cluster CC2 level combined with the resolution-of-identity approximation (RI-CC2). A detailed analysis of the meta-GGA functional performance is provided, demonstrating that they improve upon their predecessors in capturing the key electronic features of the π-conjugated two-photon absorbers. In particular, the Minnesota functional MN15 shows very promising results as it delivers pleasingly accurate chemical rankings for two-photon transition strengths and excited-state dipole moments.

Enhanced intramolecular charge transfer and near-infrared fluorescence in 4-dimethylamino-chalcone analogues through extended conjugation: synthesis, photophysical properties, and theoretical modelling.

The distinctive characteristics of near-infrared fluorescent organic molecules render them indispensable across diverse applications, from energy harvesting to bioimaging and sensing technologies. In this work, we continue our investigation on the chalcone derivative, 4-dimethylamino-2'-hydroxychalcone (nDHC, n = 1; where n is the number of olefinic bonds), by expanding the number of central double bonds (n = 2 (2DHC) and n = 3 (3DHC)). Additionally, we also synthesized the structurally related chalcones lacking the OH group (DC, 2DC, 3DC) in order to obtain a comprehensive understanding of their effects on the intramolecular charge transfer (ICT). The results show remarkable bathochromic shifts in absorption and fluorescence peaks in solution as n increases. These shifts, 20 nm and 35 nm for absorption and 100 nm and 200 nm for fluorescence in 2DHC and 3DHC, respectively, signify enhanced ICT and a significant increase in the excited state's dipole moment. The presence of OH groups notably amplifies these shifts due to additional electron donation, influencing solute-solvent interactions in solution. Femtosecond fluorescence upconversion and transient absoprtion techniques unraveled distinct dynamics in these derivatives, exhibiting the dominance of vibrational cooling, solvation, and intramolecular motions, particularly in the larger conjugated systems 3DHC and 3DC. The observed changes in the femtosecond transinet absorption spectra suggest the existence of new active states in extended conjugation systems, indicating diverse intramolecular conformational states contributing to their relaxation dynamics. The results of this study provide invaluable insights into excited-state spectroscopy, offering a roadmap for tailoring chalcone derivatives for specific applications.

Solvatochromic shifts and solvent effects on the electronic and transport behaviour of 1-Chloro Adamantane

Solvent influence on the photophysical and electronic properties of 1-Chloro Adamantane (CAD) are investigated using experimental and computational methods. Measured UV–vis absorption of CAD in various solvents exhibits substantial solvatochromatic shifts with respect to the solvent polarity. As a result of this, optical absorption of CAD undergoes the bathochromic shifts in the nonpolar solvents and hypsochromic shifts in the polar solvents with respect to polarity. Theoretical computations of EOM-CCSD and CIS quantum chemical methods calculated by means of SMD solvation model demonstrate the solvent influence on the electronic structure of CAD which are in good agreement with the experimental results. Computed results show prominent solvation effect on Lewis and non-Lewis occupancies. Large excited state dipole moment of the CAD in various solvation suggests excited states are more polarized than the ground state. In addition to this, molecular polarizabilities and energies of HOMO and LUMO show dominant solvent effects on the chemical reactivity of the CAD upon solvation. This solvent specific behaviour of CAD finds applications in optical filters with its significant hydrophobic nature.

Molecular Descriptors—Spectral Property Relations for Characterizing Molecular Interactions in Binary and Ternary Solutions, Excited State Dipole Moment Estimation

The nature and strength of the molecular interactions were established by solvatochromic studies of 22 binary and 42 ternary diluted solutions of pyridinium–carbethoxy–anilidomethylid (PCAnM). The visible absorption band of PCAnM, due to an intramolecular charge transfer (ICT) from the carbanion towards the heterocycle, shows a great sensitivity to the solvent nature. The spectral data are analysed by linear energy relationship (LERS) and the contribution of each type of interaction to the total spectral shift is estimated. The results from the solvatochromic study and those obtained by quantum mechanical computations were correlated in order to estimate the excited state dipole moment of the studied methylid. The decrease of the dipole moment by excitation emphasized in this study corresponds to the ICT nature of the visible absorption band of the solute. The ternary solutions of PCAnM achieved in mixtures of water with primary alcohols (ethanol and methanol) show the dependence of the visible band on the molar fraction of water and give the difference between the interaction energies in molecular pairs of the type water–methylid and alcohol–methylid, computed based on the statistical cell model of ternary solutions. The decrease in strength of the hydrogen bond between PCAnM and the protic solvent molecules was estimated in the following order: water > methanol > ethanol. The results from this study can be utilized in Organic Chemistry to generate knowledge of the interactions with solvents when cycloimmonium methylids are used as precursors to obtain new heterocycles and also in Quantum Chemistry to obtain a better description of their excited electronic states.

Solvent dependent nonlinear optical properties of benzodioxol chalcone: An elucidation of spectroscopic, DFT, solvatochromism and z-scan technique

Novel push–pull chalcone derivative, 3-(1,3-Benzodioxol-5-yl)-1-phenyl-2-propen-1-one (BZDP) which can exhibit fascinating third-order nonlinear optical characteristics were probed through experimental cum theoretical simulations. The structural confirmation of the molecule is analysed via spectral studies. Studied chalcone is examined for linear and nonlinear optical studies which revealing molecule's ability as an organic NLO material. The electronic transitions are reflected in the absorption and emission spectra of the examined molecule. The fluorescence quantum yield was found to be 0.12. The experimental results were reinforced by the computational simulations executed using density functional theory method. Ground and excited state dipole moments, in addition to nonlinear optical properties were evaluated by solvatochromism. NLO studies were carried out in polar and non-polar solvent media by z-scan technique. Besides, the optical limiting ability of the compound reveals that it can be used as an optical limiter.

Donor-acceptor functionalized coumarin derivatives: Synthesis, fluorescence modulation, interaction with human serum albumin and acetylcholinesterase inhibition activity

A coumarin compound 7-diethylaminocoumarin (DEAC) and its substituted derivative coumarin-6-CF3 (CCF3) were synthesized, characterized and their photophysical behavior have been investigated by steady state and time resolved fluorescence spectroscopy. Both the investigated systems show appreciable modulation in photophysical properties depending on the nature of the solvent medium and in presence of sequestering agents like cyclodextrin nanocavities and/or human serum albumin (HSA). Quantitative estimation of different solvent parameters responsible for the modulated spectral features were done from multiple linear regression analysis of the experimental data based on Kamlet-Taft and Catalán formalisms. Significant modulation in fluorescence quantum yield in polar-protic medium and/or highly viscous glycerol solution for CCF3 in comparison with the model compound DEAC was due to donor–acceptor functionalization in the former. This additional excited state charge transfer possibility led to very large excited state dipole moment change in CCF3 and resulted almost ∼ 90 nm solvent dependent fluorescence peak shift. Multi-pronged experimental results in conjunction with molecular docking calculation revealed moderate binding affinity of the investigated systems towards HSA. Additionally, the coumarin derivatives were evaluated for its anticholinergic activity using in-vitro acetylcholinesterase enzymatic assay. The results demonstrated a significant inhibition of cholinergic activity, particularly for donor–acceptor functionalized CCF3, highlighting the potential therapeutic application of it. The study provides important insights into the molecular interactions and pharmacological properties of these promising coumarin derivatives, which could serve as a basis for the development of new drug candidates targeting cholinergic pathways.

Determination of the ground and excited state dipole moments of ferulic and sinapic acids by solvatochromic effects and density function theory method

Ferulic acid (FA) and sinapic acid (SA) are groups of phenolic acids that belong to the class of hydroxycinnamic acid. Due to their molecular structure and functional groups, these compounds exhibit a wide range of biological activities. In this research, we have determined the dipole moments of these compounds in gas and solvent phases using spectroscopic and computational methods. The change in the dipole moments of FA and SA was calculated by Bakhshiev’s, Kawski–Chamma–Viallet’s, Lippert–Mataga’s, and microscopic solvent polarity functions. The results show that the change in the dipole moment calculated using Lippert–Mataga’s method is higher than that using other methods. This is due to the fact that this method ignores the specific interactions of the solute and solvent as well as the polarizability of the solute molecule. Similarly, the ground and excited-state dipole moments were determined by theoretical quantum chemical calculations using density functional theory (DFT); the results are found to be similar to the experimental ones. In both approaches, the excited dipole moment is greater than the ground state, indicating a significant redistribution of electron densities and being more sensitive to the solvent in the excited state for both molecules. The HOMO-LUMO energy bandgaps calculated in the gas phase for FA and SA are 4.001 and 4.055 eV, respectively. In addition, electron charge density maps, UV–Vis absorption spectra, and oscillator strengths were calculated using the DFT method to obtain general information about the compounds.

Systematic photophysical investigation on pyrromethene 650 laser dye: Experimental and DFT approach

In the current study, we have chosen a highly fluorescent laser dye called pyrromethene 650 (PM-650) to investigate its photophysical properties using theoretical and experimental methods. We measured the absorption and emission spectra of PM-650 in polar protic and polar aprotic solvents at ambient temperature. Bathochromic and hypsochromic shifts were observed in the absorption and fluorescence spectra of the laser dye, confirming the presence of transitions between π → π* and n → π* states. We further estimated the ground and excited state dipole moments of PM-650 through experimental (solvatochromic correlations) and theoretical (ab initio) techniques, and compared the results. Interestingly, the PM-650 displayed an increased excited state dipole moment when contrasted with its ground state. Furthermore, using the B3LYP/6-311G++(d, p) approach, we estimated the natural bond orbital and molecular electrostatic potential map of PM-650 and discussed the results. Additionally, we theoretically determined the HOMO-LUMO energy band gap of PM-650 in different solvents with varying polarities, and found good agreement with the experimentally obtained values. To assess the reactivity and softness of PM-650, we calculated global chemical reactive descriptor values based on the theoretically estimated HOMO-LUMO. Our results suggest that PM-650 is highly reactive and possesses a soft nature.

Exploration of Coumarin Derivative: Experimental and Computational Modeling for Dipole Moment Estimation and Thermal Sensing Application.

The Optical properties of the FBTC (1-((4-((5-chlorobenzo[d]oxazol-2-ylthio)methyl)-1H-1,2,3-triazol-1-yl)methyl)-3H-benzo[f]chromen-3-one) molecule were studied experimentally and theoretically. The spectra of absorption and fluorescence were recorded in various solvents to explore their Solvatochromic behavior and dipole moment at room temperature. To determine the ground and excited state of dipole moment experimentally and theoretically, we employed different Solvatochromic techniques, including microscopic solvent polarity functions developed by Lippert, Bakhshiev, Kawaski-Chamma-Viallet, and Reichardt's, as well as density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The stability of the excited state dipole moment in FBTC is higher. Using prime functional, FBTC was optimized in its ground state, and its HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital), energies were estimated. These values were then compared with those obtained through cyclic voltammetry. Based on the HOMO and LUMO values given, we calculated the global reactivity parameter and energy gap, which was found to be low at 3.77eV. This study also includes an estimation of electron absorption energies and oscillator strength. Natural population analysis (NPA), Milliken atomic charge, and molecular electrostatic potential (MESP) map are correlated. In addition, FBTC exhibited exceptional physiological temperature sensing behaviour from 20°C -65°C with high relative sensitivity and firm stability. Hence these results confirm that FBTC is a potential candidate for photonic devices and it's also applicable in optical temperature sensing.

Systematic Photophysical Interaction Studies Between Newly Synthesised Oxazole Derivatives and Silver Nanoparticles: Experimental and DFT Approach.

In this study, the photophysical properties of oxazole derivatives such as 5-(furan-2-yl) -4-tosyloxazole (OX-1) and 5-(2-bromothiazol-4-yl)-4-tosyloxazoles (OX-2) were investigated using theoretical and experimental techniques. The ground and excited state dipole moments were empirically obtained utilising the solvatochromic shift technique and several solvatochromic correlations such as Lippert's, Bakhshiev's, KawskiChamma- Viallet's, and solvent polarity equations. The ground state dipole moments, HOMO-LUMO and molecule electrostatic potential map were also computed using ab initio calculations and evaluated using Gaussian 09 W software. Furthermore, spectroscopic interactions between newly synthesised dyes (OX-1 and OX-2) and freshly synthesised silver nanoparticles (size 40nm) were studied. Increased absorbance and widening of absorption spectra for both dyes in the presence of varied quantities of silver nanoparticles show the potential of dye-nanoparticle interactions. Fluorescence quenching has been detected for both dyes in the presence of colloidal silver nanoparticles, indicating dynamic quenching, and a significant overlap between the absorption and emission spectra of the silver nanoparticle reveals that fluorescence quenching is also due to energy transfer.

Estimation of dipole moments by Solvatochromic shift method, spectroscopic analysis of UV–Visible, HOMO-LUMO, ESP map, Mulliken atomic charges, NBO and NLO properties of benzofuran derivative

Solvatochromic shift method has been used to estimate ground state (μg) and excited state (μe) dipole moments of benzofuran derivative (5NFMOT) at room temperature indifferent solvents. This method involves Lippert, Bakhshiev and Kawski-Chamma-Viallet equations. Reichardt microscopic solvent polarity parameter was used to calculate the change in dipole moment. Effect of solvents on absorption and fluorescence spectra was investigated using Kamlet and Catalan's MLR approach. Computational studies of benzofuran derivative were carried out using Gaussian 16. Geometry optimization was performed using DFT method at 6–311++G (d, p)/B3LYP basis set. UV–Visible spectra have been studied by using TD-DFT method for the same basis set. The μg was obtained from DFT method, whereas μe from TD-DFT method. It has been observed that both from experimentally and theoretically the ground state dipole moment is higher than the excited state dipole moment. HOMO-LUMO surfaces and Mulliken atomic charges have been studied in gas phase and solution. Furthermore, 3D plots of electrostatic potential map are used to identify reactive centers such as electrophilic and nucleophilic sites. NBO analysis is helpful to obtain stability and charge delocalization of the title molecule. Polarizablity, and hyper polarizability values were used to study the NLO properties.

Ground and Excited State Dipole Moments of Metformin Hydrochloride using Solvatochromic Effects and Density Functional Theory.

In this research, the ground (µg) and excited (µe) state dipole moments of metformin hydrochlorides were determined using Lippert-Mataga, Bakhshiev's, Kawski-Chamma-Viallet, and Reichardt models from fluorescence emission and UV-Vis absorption spectra in various solvents.From solvatochromic effects the calculated excited (µe) dipole moment of metformin hydrochloride were, 8.55 D, 8.34 D, 6.08 D, and 6.40 D using the Lippert-Mataga, Bakhshiev's, Kawski-Chamma-Viallet and Reichardt models respectively.The results also indicated that the dipole momentat the ground state is smaller than the excited state. This is due to solvent polarity having a stronger effect on fluorescence emission than absorption spectra.Similarly, from density functional theory, the calculated ground and excited states dipole moments of metformin hydrochloride using (DFT-B3LYP- 3-21+G*(μg= 10.02 D and μe= 11.94 D), DFT-B3LYP- 6-31+G (d, p) (μg= 8.44 D and μe= 10.87 D), and DFT-B3LYP- 6-311+G (d, p) (μg= 8.24 D and μe= 18.74 D)) analyzed by Gaussian 09W. From the optimized geometry of the molecule, the HOMO-LUMO energy band gap of metformin hydrochloride were computed using DFT [DFT-B3LYP- 3-21+G*(5.51 eV), DFT-B3LYP- 6-31+G (d, p) (5.66 eV), and DFT-B3LYP- 6-311+G (d, p) (5.70 eV)] respectively.

Unraveling the Interaction of Synthesized Thienoangelicin Derivative by Fluorescence Studies with Solvents, Bovine Serum Albumin and Metal Ions

AbstractThe growing importance of angelicin derivatives in medicine has prompted us to develop an efficient synthesis strategy for a thienoangelicin derivative, ethyl 8‐methyl‐2‐oxo‐2H‐thieno[2,3‐h]chromene‐3‐carboxylate (MTCE), and investigate its potential applications in spatial probing, therapeutics, and optical sensing. This novel fluorophore, MTCE, exhibits large Stokes shift due to the intramolecular charge separation between the thiophene and coumarin nucleus in the excited state. This indicates its potential for probing spatial polarity. Specific solute‐solvent interactions play a significant role in experimentally calculated excited state dipole moment, including long‐range electrostatic interactions and hydrogen bonding. The multi‐spectroscopic and molecular docking approaches reveal that novel MTCE also interacts in subdomain IIA of BSA by forming ground state complexes following a static quenching mechanism, with the binding constant calculated at ∼104 M−1. The complexation is spontaneous (ΔG ∼−24 kJ mol−1), and enthalpy‐driven (ΔH∼−43 kJ mol−1 and ΔS∼−61 J mol−1), and is primarily mediated by hydrogen bonding and van der Waal forces. Furthermore, the unique fluorescence selectivity of MTCE towards Fe3+ ions under neutral pH conditions, through the formation of a 1 : 1 stoichiometric complex, sets it apart from other common metal ions. Therefore, MTCE holds promising potential for effective utilization in optical sensing applications targeting metal ions.

Lagrangian Z-vector approach to Bethe-Salpeter analytic gradients: Assessing approximations.

We present an implementation of excited-state analytic gradients within the Bethe-Salpeter equation formalism using an adapted Lagrangian Z-vector approach with a cost independent of the number of perturbations. We focus on excited-state electronic dipole moments associated with the derivatives of the excited-state energy with respect to an electric field. In this framework, we assess the accuracy of neglecting the screened Coulomb potential derivatives, a common approximation in the Bethe-Salpeter community, as well as the impact of replacing the GW quasiparticle energy gradients by their Kohn-Sham analogs. The pros and cons of these approaches are benchmarked using both a set of small molecules for which very accurate reference data are available and the challenging case of increasingly extended push-pull oligomer chains. The resulting approximate Bethe-Salpeter analytic gradients are shown to compare well with the most accurate time-dependent density-functional theory (TD-DFT) data, curing in particular most of the pathological cases encountered with TD-DFT when a nonoptimal exchange-correlation functional is used.

Consistent third-order one-particle transition and excited-state properties within the algebraic-diagrammatic construction scheme for the polarization propagator.

The intermediate state representation (ISR) formalism allows for the straightforward calculation of excited state properties and state-to-state transition moments using the algebraic-diagrammatic construction (ADC) scheme for the polarization propagator. Here, the derivation and implementation of the ISR in third-order perturbation theory for the one-particle operator are presented, enabling, for the first time, the calculation of consistent third-order ADC [ADC(3)] properties. The accuracy of ADC(3) properties is evaluated with respect to high-level reference data and compared to the previously used ADC(2) and ADC(3/2) schemes. Oscillator strengths and excited state dipole moments are computed, and typical response properties are considered: dipole polarizabilities, first-order hyperpolarizabilities, and two-photon absorption strengths. The consistent third-order treatment of the ISR leads to an accuracy similar to that of the mixed-order ADC(3/2) method; the individual performance, however, depends on the property and molecule under investigation. ADC(3) produces slightly improved results in the case of oscillator strengths and two-photon absorption strengths, while excited state dipole moments, dipole polarizabilities, and first-order hyperpolarizabilities exhibit similar accuracy at ADC(3) and ADC(3/2) levels. Taking the significant increase of central processing unit time and memory requirements of the consistent ADC(3) approach into account, the mixed-order ADC(3/2) scheme offers a better compromise between accuracy and efficiency for the properties considered.

Gauge-Invariant Excited-State Linear and Quadratic Response Properties within the Meta-Generalized Gradient Approximation.

Gauge invariance is a fundamental symmetry connected to charge conservation and is widely accepted as indispensable for any electronic structure method. Hence, the gauge variance of the time-dependent kinetic energy density τ used in many meta-generalized gradient approximations (MGGAs) to the exchange-correlation (XC) functional presents a major obstacle for applying MGGAs within time-dependent density functional theory (TDDFT). Replacing τ by the gauge-invariant generalized kinetic energy density τ̂ significantly improves the accuracy of various functionals for vertical excitation energies [R. Grotjahn, F. Furche, and M. Kaupp. J. Chem. Phys. 2022, 157, 111102]. However, the dependence of the resulting current-MGGAs (cMGGAs) on the paramagnetic current density gives rise to new exchange-correlation kernels and hyper-kernels ignored in previous implementations of quadratic and higher-order response properties. Here we report the first implementation of cMGGAs and hybrid cMGGAs for excited-state gradients and dipole moments, as well as an extension to quadratic response properties including dynamic hyperpolarizabilities and two-photon absorption cross sections. In the first comprehensive benchmark study of MGGAs and cMGGAs for two-photon absorption cross sections, the M06-2X functional is found to be superior to the GGA hybrid PBE0. Additionally, two case studies from the literature for the practical prediction of nonlinear optical properties are revisited and potential advantages of hybrid (c)MGGAs compared to hybrid GGAs are discussed. The effect of restoring gauge invariance varies depending on the employed MGGA functional, the type of excitation, and the property under investigation: While some individual excited-state equilibrium structures are significantly affected, on average, these changes result in marginal improvements when compared against high-level reference data. Although the gauge-variant MGGA quadratic response properties are generally close to their gauge-invariant counterparts, the resulting errors are not bounded and significantly exceed typical method errors in some of the cases studied. Despite the limited effects seen in benchmark studies, gauge-invariant implementations of cMGGAs for excited-state properties are desirable from a fundamental perspective, entail little additional computational cost, and are necessary for response properties consistent with cMGGA linear response calculations such as excitation energies.