Intermolecular Charge Transfer Interaction Research Articles

Pagoda[5]arene with Large and Rigid Cavity for the Formation of 1∶2 Host–Guest Complexes and Acid/Base-Responsive Crystalline Vapochromic Properties

Pagoda[5]arene (P5), which is composed of five 2,6-dimethoxylanthracene (2,6-DMA) subunits bridged by methylene groups at 1,5 positions, was conveniently synthesized in 43% by trifluoroacetic acid ...

Study of geometric, electronic structures and vibrations of 4, 4′, 4′′, 4′′′-(porphine-5,10,15,20 tetrayl) tetrakis (benzene sulfonic acid) compound by computational and experimental techniques

The optimized geometry and vibrational frequencies of a substituted compound of tetraphenylporphine namely 4, 4[Formula: see text], 4[Formula: see text], 4[Formula: see text]-(porphine-5,10,15,20 tetrayl) tetrakis (benzene sulfonic acid) have been investigated using density functional theory. The vibrational spectra of tetraphenylporphine and its substituted complex were simulated to study the substitution effects of sulfonic acid group at the peripheral sites of tetraphenylporphine. Experimentally, vibrational properties of these molecules have been studied using infrared absorption spectroscopic technique. The vibrational frequencies obtained from the theoretical studies generally agree with the experimental values. For substituted molecules, due to a change in charge distribution, ring vibrations accompanied by the S–O motions also appear at the higher wavenumbers. In the lower region, C–H bending vibrations diminish and SO3 group vibrations arise. The electronic absorption spectra of the substituted tetraphenylporphine in different solvents have been studied using UV-vis spectroscopy. In addition to dipole-dipole and electrostatic interactions, hydrogen bonding plays a key role in molecular-solvent interactions. The energy gap between the highest occupied and lowest unoccupied molecular orbitals and natural bonding orbital analysis show the intermolecular charge transfer interactions. The molecular electrostatic potential and solvent accessible surface area analysis were made in order to study the interaction sites of the molecules. The current-voltage characteristics for the substituted molecule were also plotted. It was found that substituted tetraphenylporphine show good photoconductivity.

Cocrystal Engineering: Toward Solution‐Processed Near‐Infrared 2D Organic Cocrystals for Broadband Photodetection

Large-area 2D cocrystals with strong near-infrared (NIR) absorption have been designed and prepared. Driven by the intermolecular charge-transfer (CT) interactions, zinc tetraphenylporphyrin (donor) and C60 (acceptor) self-assemble into a NIR cocrystal with absorption wavelength up to 1080 nm. By tailoring the growth solvents and processes, the cocrystal morphologies can be tuned from 1D nanowires, 2D nanosheets to large-area 2D cocrystal films with length reaching several millimeters. Owing to the highly ordered donor-acceptor arrangement, the CT absorption in the 2D cocrystals is enhanced and is comparable to singlet absorption. The uniform 2D cocrystals, with enhanced CT absorption in the NIR region, displays a high responsivity of 2424 mA W-1 to NIR light and a fast response time of 0.6 s. The excellent device performance is attributed to the generation of long-lived free charge carriers as revealed by transient absorption spectroscopy and optimization of device configuration.

Ultrafast electron transfer in all-small-molecule photovoltaic blends promoted by intermolecular interactions in cyanided donors

Cyano substitution has been established as a viable approach to optimize the performance of all-small-molecule organic solar cells. However, the effect of cyano substitution on the dynamics of photo-charge generation remains largely unexplored. Here, we report an ultrafast spectroscopic study showing that electron transfer is markedly promoted by enhanced intermolecular charge-transfer interaction in all-small-molecule blends with cyanided donors. The delocalized excitations, arising from intermolecular interaction in the moiety of cyano-substituted donor, undergo ultrafast electron transfer with a lifetime of ~3 ps in the blend. In contrast, some locally excited states, surviving in the film of donor without cyano substitution, are not actively involved in the charge separation. These findings well explain the performance improvement of devices with cyanided donors, suggesting that manipulating intermolecular interaction is an efficient strategy for device optimization.

Design of Thienothiophene-Based Copolymers with Various Side Chain-End Groups for Efficient Polymer Solar Cells.

Three two-dimensional donor–acceptor conjugated copolymers consisting of a benzo[1,2-b:4,5-b′]dithiophene derivative and thieno[3,2-b]thiophene with a conjugated side chain were designed and synthesized for use in bulk heterojunction (BHJ) or nonfullerene polymer solar cells (PSCs). Through attaching various acceptor end groups to the conjugated side chain on the thieno[3,2-b]thiophene moiety, the electronic, photophysical, and morphological properties of these copolymers were significantly affected. It was found that the intermolecular charge transfer interactions were enhanced with the increase in the acceptor strength on the thieno[3,2-b]thiophene moiety. Moreover, a better microphase separation was obtained in the copolymer: PC71BM or ITIC blend films when a strong acceptor end group on the thieno[3,2-b]thiophene moiety was used. As a result, BHJ PSCs based on copolymer:PC71BM blend films as active layers exhibited power conversion efficiencies from 2.82% to 4.41%, while those of nonfullerene copolymer:ITIC-based inverted PSCs ranged from 6.09% to 7.25%. These results indicate the side-chain engineering on the end groups of thieno[3,2-b]thiophene unit through a vinyl bridge linkage is an effective way to adjust the photophysical properties of polymers and morphology of blend films, and also have a significant influence on devices performance.

Investigation on structural, optical, mechanical, thermal and nonlinear optical activity of 2-methylazinium (2,4,6)-trinitrophenolate – experimental and DFT approach

Organic nonlinear optical single crystal of 2-methylazinium (2,4,6)-trinitrophenolate (2MATNP) was grown by slow evaporation technique at room temperature. The structural parameters were analyzed by single crystal x-ray diffraction analysis which reveals that the 2MATNP crystallizes in triclinic crystal system with P1¯ space group. The intermolecular interactions present in the 2MATNP were pictorially explained by using Hirshfeld surface analysis. The functional groups present in the synthesized crystal lattice were analysed with FTIR and FT-Raman spectral studies. The transmittance ability of the grown 2MATNP was studied by using UV-visible transmittance spectral analysis and the optical band gap was evaluated. NBO analysis confirms the hydrogen bonding and hyperconjugative interactions whereas the nature of atomic charges was explained by Natural Population analysis. The global reactivity descriptors and the intermolecular charge transfer interactions were analyzed by using HOMO-LUMO and MESP analysis. Nonlinear optical property was studied experimentally and theoretically which indicates the effective nonlinear optical efficiency of grown 2MATNP single crystal. The mechanical stability of the grown 2MATNP was analyzed by using Vicker's microhardness test. Thermal behavior has been analysed by TG/DTA analysis.

Highly Stable Supramolecular Donor-Acceptor Complexes Involving a Bis(18-Crown-6)azobenzene as Weak Donor: Structure-Property Relationships.

The physicochemical properties of highly stable supramolecular donor–acceptor (D–A) complexes of a bis(18-crown-6)azobenzene (weak π-donor) with a series of bis(ammonioalkyl) derivatives of viologen-like molecules (π-acceptors) in acetonitrile were studied using cyclic voltammetry, UV–vis absorption spectroscopy, 1H NMR spectroscopy, and density functional theory (DFT) calculations. The crystalline structures of the bis(crown)azobenzene and its complex with a bis(ammoniopropyl) derivative of 2,7-diazapyrene were determined by X-ray diffraction analysis. In solution, all of the supramolecular D–A complexes studied have a pseudocyclic structure owing to ditopic coordination of the ammonium groups of the acceptor to the crown ether moieties of the donor. These complexes show somewhat lower stability as compared with the previously studied complexes of the related derivative of stilbene (strong π-donor), which is explained by the relatively weak intermolecular charge-transfer (CT) interactions. Time-dependent DFT calculations predict that the low-energy CT transition in the D–A complex of the bis(crown)azobenzene with a bis(ammoniopropyl) derivative of 4,4′-bipyridine lies between the local ππ* and nπ* transitions of the azobenzene. The absorption band associated with the CT transition is indiscernible in the spectrum since it is overlapped with broad and more intense ππ* and nπ* bands. It was found that the E → Z photoisomerization quantum yield of the bis(crown)azobenzene decreases by almost an order of magnitude upon the complexation with the 4,4′-bipyridine derivative. This effect was tentatively attributed to the intermolecular electron transfer that occurs in the 1ππ* excited state of the azobenzene and competes with the 1ππ* → 1nπ* internal conversion.

Separation of toluene from benzene derivatives and extraction of toluene from water based on a flexible naphthalene diimide coordination network

The separation of toluene derivatives from each other is an important, challenging, and energy exhaustive process in chemical industry. Here we report a new flexible coordination network, [Cu(4-pmntd)2(NO3)2](4-pmntd = N, N’-Bis(4-pyridymethy)naphthalene diimide), that exhibits not only selective separation of toluene over benzene and xylene, but also can straight extract toluene from water. The high performance for selective adsorption of toluene was validated by single-crystal XRD, vapor sorption isotherms, and NMR. The detailed structural information discloses that the naphthalene diimide derivative ligand can form intermolecular charge-transfer interactions with toluene, and thus highly selective capture toluene with its derivatives. Naphthalene diimide ligand engenders favorable aromatic π interactions for its electron-deficient and planar aromatic surface. The electron giving substituents on aromatic ring cause an overall change in the cloud density, which can be employed in separating toluene derivatives. When 1:1 toluene/benzene mixture pass through a fixed-bed packed column with this coordination network, 96% purity of benzene can be directly produced during the first adsorption cycle. The outlet xylene purity was raised from 50% to 85% when 1:1 toluene/xylene mixture pass through the porous materials. The separation performance of the coordination network could be used for industrial separation of toluene derivatives with a low energy cost at room temperature.

Two-photon excited deep-red and near-infrared emissive organic co-crystals

Two-photon excited near-infrared fluorescence materials have garnered considerable attention because of their superior optical penetration, higher spatial resolution, and lower optical scattering compared with other optical materials. Herein, a convenient and efficient supramolecular approach is used to synthesize a two-photon excited near-infrared emissive co-crystalline material. A naphthalenediimide-based triangular macrocycle and coronene form selectively two co-crystals. The triangle-shaped co-crystal emits deep-red fluorescence, while the quadrangle-shaped co-crystal displays deep-red and near-infrared emission centered on 668 nm, which represents a 162 nm red-shift compared with its precursors. Benefiting from intermolecular charge transfer interactions, the two co-crystals possess higher calculated two-photon absorption cross-sections than those of their individual constituents. Their two-photon absorption bands reach into the NIR-II region of the electromagnetic spectrum. The quadrangle-shaped co-crystal constitutes a unique material that exhibits two-photon absorption and near-infrared emission simultaneously. This co-crystallization strategy holds considerable promise for the future design and synthesis of more advanced optical materials.

Spectral bio-markers, hirshfeld analysis, molecular docking and cytotoxicity of bronchodilatic drug 1,3-dimethylxanthine: A vibrational approach

The drug action of Bronchodilatic Drug 1,3-dimethylxanthine (THP) are mediated by the inhibition of phosphodiesterase (PDE) and increase of intracellular cyclic adenosine monophosphate (cAMP) which mediates smooth muscular mediations. The vibrational spectral investigations of THP and the bio-markers of methylxanthine bronchodilators along with DFT computations explains the structural and bonding features, charge-transfer interactions, nature of hydrogen bonding etc. The strong and simultaneous occurrence of 8a mode in IR and Raman spectra reveals the involvement of benzene ring in the intermolecular charge transfer interaction through NH⋯O hydrogen bonding. The spectral bio-marker bands of methylxanthine based bronchodilatic drugs, corresponding to ring CC stretching ca 1599 cm−1 (8a mode) and CO stretching vibrations ca 1650 cm−1 stretching vibrations are found to be strongly and simultaneously active in both IR and Raman spectra as observed in other bronchodilators viz, caffeine and theobromine. It is observed that the THP molecule possesses reasonably high dipole moment results in moderate βtotal value which favours charge transfer interactions that help in binding with the receptor phosphodiesterase enzyme. THP in the binding pocket is stabilized through the attractive non-covalent T-shaped π-π interaction, π-cation interactions and π-alkyl interactions between the aromatic rings of THP with the amino acid residues suggest that through these interactions the ligand THP binds with albumin protein that inhibits the synthesis of phosphodiesterase enzyme and other mediators in the process of improving its anti-asthmatic activity.

Intermolecular Charge-Transfer Modulates Liquid-Liquid Phase Separation and Liquid-to-Solid Maturation of an Intrinsically Disordered pH-Responsive Domain.

Liquid-liquid phase separation of intrinsically disordered proteins into mesoscopic, dynamic, liquid-like supramolecular condensates is thought to govern critical cellular functions. These condensates can mature from a functional liquid-like state to a pathological gel-like or solid-like state. Here, we present a unique case to demonstrate that an unusual cascade of intermolecular charge-transfer coupled with a multitude of transient noncovalent interactions and conformational fluctuations can promote liquid phase condensation of a pH-responsive, intrinsically disordered, oligopeptide repeat domain of a melanosomal protein. At neutral cytosolic pH, the repeat domain forms highly dynamic, mesoscopic, permeable, liquid-like droplets possessing rapid internal diffusion and torsional fluctuations. These liquid condensates mature via pervasive intermolecular charge-transfer and persistent backbone interactions driving the liquid-to-solid phase transition into heterogeneous solid-like aggregates that are structurally and morphologically distinct from typical amyloids formed at mildly acidic melanosomal pH. Our findings reveal the regulatory role of the repeat domain as a specific pH-sensor that critically controls the phase transition and self-assembly processes akin to prion-like low-complexity domains modulating intracellular phase separation.

Anisotropic photoconductivity of aromatic and semi-aliphatic polyimide films: Effects of charge transfer, molecular orientation, and polymer chain packing

The anisotropic photoconductive properties of polyimide (PI) films prepared using seven types of dianhydrides and a diamine containing a diphenyl-benzidine structure featuring rigid linear structure and strong electron-donating ability were analyzed. Photoirradiation wavelength dependences of the in-plane and out-of-plane photocurrents, which are known as anisotropic photocurrent spectra, were investigated in comparison with optical absorption spectra, the degrees of molecular aggregation, in-plane/out-of-plane orientation of PI chains, and ordered structures formed in film state. We have previously reported that intermolecular charge transfer (CT) interaction is a key factor for increasing the out-of-plane photoconductivity of PI films because they determine the efficiency of charge separation. However, when sufficient charge carriers are generated in thin PI films via photo irradiation, in which penetration depth of irradiated light is sufficiently larger than the film thickness, suppression of charge recombination by reducing molecular chain packing is rather effective at enhancing both the in-plane and out-of-plane photoconductivity. This is because the mobility of carriers is significantly increased in the dense aggregation structures, and thus collisions between carriers becomes more frequent, which led to higher recombination efficiency. Furthermore, the photocurrent anisotropy was increased as the degree of in-plane orientation of the main PI chains increased, which agrees with the fact that charged carriers are preferentially transported between PI chains. Accordingly, promoting charge transport efficiency by reducing PI chain packing and increasing the out-of-plane orientation of PI chains are essential to increase the in-plane photoconductivity of PI films.

Experimental and quantum chemical studies on SHG, Z-scan and optical limiting investigation of 2-amino-5-bromopyridinium trifluoroacetate single crystal for optoelectronic applications

The 2-amino-5-bromopyridinium trifluoroacetate (2A5BPTFA) crystal has been successfully grown by solvent slow evaporation technique. The grown crystal is found to non-centrosymmetric space group Pna21 with orthorhombic crystal system, which has been confirmed from single crystal X-ray diffraction analysis. The crystalline nature of the 2A5BPTFA is supported by powder X-ray diffraction technique. The molecular structure and different functional groups in 2A5BPTFA were confirmed by 1H, 13C NMR and FTIR spectral analyses. The intermolecular charge transfer that occurs in 2A5BPTFA molecule due to the presence of N–H⋯O and C–H⋯O hydrogen bondings have been studied by Hirshfeld surface analysis. From the UV–Vis absorption and photoluminescence spectra, the lower cutoff wavelength and emission peak are found to be 364 nm and 392 nm, respectively. In addition, the optical band gap of grown crystal has been calculated as 3.47 eV. Powder second harmonic generation efficiency of the crystal is observed to be 2.44 times greater than that of potassium dihydrogen phosphate. A positive photoconducting nature and low dielectric constant values have been obtained from photoconductivity and dielectric studies. From the Z-scan study reveals the self-defocusing nature of the grown crystal. Optical limiting study shows the optical limiting response of 2A5BPTFA crystal. In addition, the intermolecular charge transfer interactions and existence of N–H⋯O hydrogen bonding of the 2A5BPTFA have been confirmed by density functional theory methods and are discussed in detail.

Solvation-Enhanced Intermolecular Charge Transfer Interaction in Organic Cocrystals: Enlarged C-C Surface Close Contact in Mixed Packing between PTZ and TCNB.

The mixed π–π packing of the donor (D) and acceptor (A) molecules is the highlighting feature of the intermolecular interactions following charge transfer (CT) issues in organic cocrystal systems. There is an inverse relationship between the D–A interplanar distance and the intermolecular CT interaction. However, the D–A C–C surface close contact (relative areas) on the intermolecular CT interactions in organic cocrystal systems is rarely investigated. Herein, we designed and constructed a novel cocrystal and its solvate cocrystal. The structural and electrostatic potential analyses suggest that the solvation destroys the N–H···N hydrogen bond interaction between phenothiazine (PTZ) and 1,2,4,5-tetracyanobenzene (TCNB), which causes the TCNB molecules to have a 90° rotation along the normal axis of the PTZ plane. Thus, the D–A C–C surface close contact is enlarged, strengthening the intermolecular π–π stacking interactions and intermolecular CT interaction between PTZ and TCNB, which are further evidenced by the absorption and Raman spectroscopic analyses. This study provides rare evidence of the enlarged C–C surface close contact in the mixed packing between D and A that greatly contributes to the intermolecular CT interaction in a D–A cocrystal system. It also provides a deeper understanding of the role of solvation in the structure–property relationship of organic cocrystal materials.

Anomalous Halogen–Halogen Interaction Assists Radial Chromophoric Assembly

The design of highly efficient supramolecular architectures that mimic competent natural systems requires a comprehensive knowledge of noncovalent interactions. Halogen bonding is an excellent noncovalent interaction that forms halogen-halogen (X2) as well as trihalogen interacting synthons. Herein, we report the first observation of a symmetric radial assembly of chromophores ( R3̅ c space group) composed of a stable hexabromine interacting synthon (Br6) that further push the limits of our understanding on the nature, role, and potential of noncovalent halogen bonding. Contrary to the destabilization proposed for Type-I X2 interactions, Br6-synthon-possessing Type-I X2 interactions exhibit a stabilizing nature owing to the exchange-correlation component. The radial assembly of chromophores is further strengthened by intermolecular through-space charge transfer interaction. Br6-synthon-driven 3-fold symmetric radial assembly render a lattice structure that reminisces the chromophoric arrangement in the light harvesting system 2 of purple bacteria.

Vibrational spectra, dielectric properties, conductivity mechanisms and third order nonlinear optical properties of guanidinium 4-aminobenzoate

The frequency response of dielectric permittivity measurements at temperatures 35 °C and 100 °C suggests enhanced inherent optical quality and few defects in the crystal. The Cole-Cole plot shows the presence of grain and grain boundary, it is found that single relaxation is observed in the crystal. The ac and dc conductivity and dielectric behavior of the grown crystal were systemically investigated as a function of frequency and temperature. The third order nonlinear optical property extensively studied by z-scan technique revealed high third order nonlinearity in the form of self-defocusing and two-photon absorption with saturable absorption. The strong intermolecular charge transfer interaction evident from NBO and AIM studies confirms the NLO property of the material. The detailed vibrational assignments were carried out on the basis of potential energy distribution (PED) analysis and scaled quantum mechanical force field calculation using MOLVIB program. The red shifted NH stretching wavenumbers and the broadening of corresponding bands in the solid state as well as the gas phase spectra, optimized molecular geometry and NBO analysis have confirmed the presence of N-H⋯O hydrogen bonding in G4AB.

Exploring the spectral features and quantum chemical computations of a novel biologically active heterocyclic class of compound 2MEFPBA dye: Experimental and theoretical approach

Abstract Here we report, experimental and theoretical determination of ground and excited state dipole moments of the class of heterocyclic compound namely 2-Methoxy-5-fluoro phenyl boronic acid (2MEFPBA) dye. Bathochromic shift with increasing solvent polarity is observed indicating π →π* transition due to intermolecular charge transfer interactions. The ground and excited state dipole moments are found to be parallel to each other. The molecular structure, Frontier molecular orbital (FMO), natural bond orbital (NBO) analysis and nonlinear optical (NLO) properties of 2MEFPBA have been investigated using the Density Functional Theory with B3LYP/6‒31 ++ g (d,p) basis set. Chemical reactivity and kinetic stability of 2MEFPBA are analyzed using FMO energy. Polarizability and hyperpolarizability computations are used to determine the NLO properties, whereas natural bond orbital (NBO) analysis showed the proton transfer within the selected donor-acceptor depicting large energy of stabilization for the compound under study.

Spectroscopic behavior, FMO, NLO and NBO analysis of two novel aryl boronic acid derivatives: Experimental and theoretical insights

Here we report, experimental and theoretical determination of ground and excited state dipole moments of aryl boronic acid derivatives, 2-Bromophenyl boronic acid (2BPBA) and 2-Isopropylphenyl boronic acid (2IPBA). In both the compounds, Bathochromicshift is observed with increasing solvent polarity indicating π →π* transition due to intermolecular charge transfer interactions. For both the compounds, the ground and excited sate dipole moments are parallel to each other. The excited state dipole moment (μe) is greater than ground state dipole moment (μg) for the compound 2IPBA where as for 2BPBA, excited state dipole moment (μe) is less than ground state dipole moment (μg). Further, experimentally obtained Δμ are compared with those using microscopic empirical solvent polarity (ETN). In parallel, the use of Kamlet-Taft parameters to the solvent effect on spectral properties of 2BPBA and 2IPBA are also discussed. The molecular structure, Frontier Molecular Orbitals (FMO), Natural Bond Orbital (NBO) analysis, Non-Linear Optical (NLO) properties of 2BPBA and 2IPBA have been investigated using the (DFT) calculations with B3LYP/6‒311++G (d, p) basis set. The chemical reactivity and kinetic stability of the compounds is shown by differences between the energy levels by analyses of Frontier molecular orbitals. The polarizability and hyperpolarizability computations determine the NLO properties, whereas Natural bond orbital (NBO) analysis showed proton transfer within the selected donor-acceptor depicting large energy of stabilization for the compounds under study.

TD-DFT Calculations, NBO, NLO Analysis and Electronic Absorption Spectra of Some Novel Thiazolo[3,2-a]Pyridine Derivatives Bearing Anthracenyl Moiety

The electronic structure and spectra of the studied compounds 1–4 are investigated using TD-DFT/B3LYB/6-311G (d, p) level of theory. The results of calculations show that all the studied compounds 1–4 are non-planar, as indicated from the dihedral angles. The electronic absorption spectra of the studied compounds are recorded in the UV-VIS region, in both Acetone (as polar solvent) and Xylene (as non-polar solvent). The observed vertical electronic transitions assignments are facilitated via time-dependent density functional theory TD-DFT. Solvent dependence of the band maxima (λmax) and intensities of the observed spectra are explained in terms of blue and red shifts. Electronic configurations contributing to each excited state are identified and the relevant MOs are characterized. The natural bond orbital (NBO) analysis were discussed in terms of the extent of delocalization, intermolecular charge transfer and second order perturbation interactions between donor and acceptor MOs. The Coulomb-attenuating method (CAM-B3LYP) and Corrected Linear Response Polarizable Continuum Model (CLR) PCM studied for theoretically obtaining the electronic absorption spectra in gas phase, Acetone and Xylene, respectively, indicate a good agreement with the observed spectra. The calculated nonlinear optical parameters (NLO); polarizibilty (α), anisotropy of the polarizibility (Δα) and first order hyperpolarizibility (β) of the studied compounds show promising optical properties. The HOMO-LUMO energy gap helped in analyzing the chemical reactivity, hardness, softness, chemical potential and electro negativity. 3D-plots of the molecular electrostatic potential (MEP) for the studied compounds are investigated and analyzed showing the distribution of electronic density of orbital's describing the electrophilic and nucleophilic sites of the selected molecules.

Attraction between electrophilic caps: A counterintuitive case of noncovalent interactions.

Intermolecular attractive interaction between electrophilic sites is a counterintuitive phenomenon, as the electrostatic interaction therein is repulsive and destabilizing. Here, we confirm this phenomenon in four representative complexes, using state-of-the-art quantum mechanical methods. By employing the block-localized wavefunction (BLW) method, which can turn off intermolecular charge transfer interactions, we profoundly demonstrated the significance of charge transfer interactions in these seemingly counterintuitive complexes. Indeed, after being "turned off" the intermolecular charge transfer interaction in, for example, the FNSi···BrF complex, the originally attractive intermolecular interaction turns to be repulsive. The energy decomposition approach based on the BLW method (BLW-ED) can partition the overall stability gained on the formation of intermolecular noncovalent interaction into several physically meaningful components. According to the BLW-ED analysis, the electrostatic repulsion in these counterintuitive cases is overwhelmed by the stabilizing polarization, dispersion interaction, and most importantly, the charge transfer interaction, resulting in the eventual counterintuitive overall attraction. The present study suggests that, predicting bonding sites of noncovalent interactions using only the "hole" concept may be not universally sufficient, because other significant stabilizing factors will contribute to the stability and sometimes, play even bigger roles than the electrostatic interaction and consequently govern the complex structures. © 2018 Wiley Periodicals, Inc.