Photophysics and Structure of Inclusion Complex of 4,4-Diaminodiphenyl Sulfone with Cyclodextrin Nanocavities (original) (raw)
Related papers
Journal of inclusion phenomena and macrocyclic chemistry, 2005
The absorption and fluorescence spectral characteristics of 2-aminodiphenylsulphone (2ADPS) have been investigated in the presence of b-cyclodextrin (b-CDx) in water. Dual emission is observed upon the complexation of 2ADPS in b-CDx. The stoichiometry of the host:guest inclusion complex is found to be 2:1. Steady state and timeresolved fluorescence spectral analysis support the formation of 2:1 complex between b-CDx and 2ADPS. The large enhancement in fluorescence intensity of twisted intramolecular charge transfer (TICT) band in aqueous b-CDx solution is due to the decrease in non-radiative processes. The ground and the excited state pK a values for the monocation-neutral equilibrium of 2ADPS in b-CDx are found to be different from the pK a values in aqueous solution. In the presence of b-CDx, 2ADPS is found to be less basic in the ground and the excited states.
Journal of Chemical Research, 2006
Analysis of the absorption and fluorescence characteristics of 4,4′-diaminodiphenylsulfone (4DADPS) in aqueous β-cyclodextrin (β-CDx) solution under different acidic conditions reveals that: (i) the twisted intramolecular charge transfer state (TICT) is more populated than the locally excited (LE) state of 4DADPS in β-CDx; and (ii) the protonation of the monocation of 4DADPS in the S0 and S1 states in β-CDx requires more acidic conditions than in the absence of β-CDx. The higher stabilisation of the TICT state compared to the LE state of 4DADPS in β-CDx inclusion complex is contrary to normal observation. This anomalous behaviour is explained by the geometry of the 1: 1 inclusion complex.
Inclusion as a driving force for the intramolecular charge transfer (ICT) fluorescence of p-(N,N-diphenylamino)benzoic acid methyl ester (DPABME) in a-cyclodextrin (a-CD) aqueous solution Abstract A 1:1 inclusion complex between p-(N,N-diphenylamino)benzoic acid methyl ester (DPABME) molecule and a-cyclodextrin (a-CD) in aqueous solution is formed with a stabilization constant of ca. 45.65 ± 3.59 M-1 at 25 °C. The formation of the complex is accompanied by enhancement of the long wavelength fluorescence at 510 nm (attributed to intramolecular charge transfer (ICT) due to twisting) relative to the normal fluorescence at 420 nm. In water, the long-wavelength fluorescence is hidden under the red tail of the normal fluorescence band due to quenching by non-radiative transition. Inclusion by CD reduces quenching and thus constitutes a driving force for DPABME to emit at longer wavelength via ICT process. Keywords Guest–host inclusion Á Intramolecular charge transfer Á Fluorescence Á p-(N,N-diphenylamino)benzoic acid methyl ester (DPABME) Á Cyclodextrins
The Journal of Physical Chemistry, 1995
A 1 : 1 complex of 6-O-a-~-glucosyl-~-cyclodextrin (GI-B-CD) with 4-(dimethy1amino)benzonitrile (DMABN) associates with itself in aqueous solutions at high concentrations into a 2:2 complex (homodimer). The 1:l complex of GI-B-CD with DMABN also makes a heterodimer (1:1:2 complex) by the association with a 1:l inclusion complex of another guest molecule such as 1-pentanol, benzene, anisole, and benzonitrile. The association of the complex is accompanied by a drastic change in the fluorescence spectrum of DMABN. The measurement of the fluorescence intensity as a function of the concentration of GI-B-CD gave the equilibrium constants for the association. The equilibrium constants were greatly dependent on the temperature, and the values for both AH and AS were largely negative. The fluorescence spectra of DMABN in the cavity of the dimers changed with exchanging the second guest compound, which implies that the second guest molecule plays the role of a polar solvent in the nonpolar environment in the cavity. The formation of homo-and heterodimers of the 1:l inclusion complex also takes place in the solutions containing other cyclodextrins and DMABN.
Driving forces and electronic structure in β-cyclodextrin/3,3′-diaminodiphenylsulphone complex
Journal of Molecular Liquids, 2014
The complexation of 3,3′-diaminodiphenylsulphone (3DADPS) by β-cyclodextrin (β-CD) was analyzed using PM6 method and several combinations of ONIOM2 hybrid calculations in vacuum and in water. The objective was to elucidate electronic structure, driving forces and energy changes that accompany the complexation. Complexation and interaction energies, thermodynamic parameters, chemical reactivity and site selectivity of the molecular systems have been investigated. The results show that the inclusion process is exothermic. NBO calculations reveal that hydrogen bonding between β-CD and 3,3′-diaminodiphenylsulphone is a major factor contributing to the overall stability of the complex.
Journal of Molecular Liquids, 2020
In this study we report on steady state absorption, emission, and time resolved fluorescence emission studies of 2-naphthylamine-6-sulfonate (2NA6S) and 1-naphthylamine-4-sulfonate (1NA4S) compounds in neutral aqueous solution and when added to different cyclodextrin derivatives (CDs) such as α-, β-, γ-, methyl-β-and 2-(hydroxypropyl) β-cyclodextrin. Steady state measurements reveal that 2NA6S and 1NA4S form 1:1 inclusion complexes with the studied cyclodextrin derivatives. Steady state absorption measurements show a considerable change in 2NA6S spectrum upon addition to β, methyl βand 2-(hydroxypropyl) β-cyclodextrin with association constants, K a , of 70.0, 160.0 and 20.0 M −1 , respectively, while no change was observed upon the addition of α-CD or γ-CD to its aqueous solution. Addition of the studied CDs to 1NA4S did not show any changes to its absorption spectrum, indicating a very weak interaction in the ground state in this case. In contrast to the weak changes observed in the absorption spectra of the host compounds, changes in their corresponding steady state fluorescence emission spectra were much pronounced with an association constants, K f , of 20.0, 220.0, 42.0, 550.0, and 110.0 M −1 when 2NA6S was included in α-, β-, γ-, methyl-β-and 2-(hydroxypropyl)-β-cyclodextrin, and 57.0, 420.0 and 110.0 M −1 when 1NA4S was included in β, methyl βand 2-(hydroxypropyl) β-cyclodextrin, respectively. Fluorescence decay traces of 2NA6S and 1NA4S were found to fit well with biexponential decay function in the absence and presence of the studied CDs. Fluorescence decay changes were very noticeable in case of 2NA6S inclusion in β-CD with an association constant very close to that obtained from steady state fluorescence measurements. 1 H NMR measurements have been used to confirm the inclusion of 2NA6S and the partial inclusion of 1NA4S in the cyclodextrin derivatives.
Journal of Inclusion …, 1998
Using a simple molecular mechanics approach interaction energy profiles of simple probes (C, CH 4 , C 6 H 6 , H 2 O, NH + 4 , and HCOO − ) passing through the center of the β-CD ring cavity along the main molecular symmetry axis were first evaluated. Molecular Electrostatic Potential (MEP) values along the same path were also evaluated. The effect of the flexibility of the host β-CD molecule together with solute-solvent (H 2 O) interactions have been represented by averaging structures of MD calculations for β-CD alone and β-CD surrounded by 133 H 2 O molecules. The effect of various substitutions of β-CD has also been evaluated. Small symmetric hydrophobic probes (such as C, CH 4 , C 6 H 6 ) are predicted to form stable inclusion complexes with non-substituted and substituted β-CDs, the probe position typically being near the cavity center. The stability of the inclusion complexes will increase with increasing size and aliphatic character of the probe. Small polar and charged probes (such as H 2 O, NH + 4 , HCOO − ) are predicted to prefer the interaction with the solvent (water) in the bulk phase rather than the formation of inclusion complexes with non-substituted and substituted β-CDs. Guest-host interactions in the stable inclusion complexes with hydrophobic probes are almost entirely dominated by dispersion interactions. The MEP reaches magnitudes close to zero in the center of the non-substituted β-CD ring cavity and in most of the studied substituted β-CDs and shows maximum positive or negative values outside of the cavity, near the ring faces. Substitution of β-CD by neutral substituents leads to enhanced binding of hydrophobic probes and significant changes in the MEP profile along the β-CD symmetry axis.
Colloids and Surfaces B-biointerfaces, 2008
On the line of a previous work on the spectral properties of some of heteroaryl chalcone, the absorption and fluorescence emission spectral properties of 3-(4′-dimethylaminophenyl)-1-(2-furanyl)prop-2-en-1-one (DMAFP), have been investigated in organized media of aqueous micellar and β-cyclodextrin (β-CD) solutions. While the absorption spectra are less sensitive to the nature of the added surfactant or β-CD, the characteristics of the intramolecular charge transfer (ICT) fluorescence are highly sensitive to the properties of the medium. The ICT maximum is strongly blue-shifted with a great enhancement in the fluorescence quantum yield on adding micellar or β-CD. This indicates the solubilization of DMAFP in the micellar core and formation of an inclusion complex with β-CD. The critical micelle concentrations (CMC) as well as the polarity of the micellar core of SDS, CTAB and TX-100 have been determined. The CMC values are in good agreement with the reported values while the polarity is lower indicating that DMAFP molecules are incorporated in the micellar core not at the micellar interface. The inclusion constants of binding of DMAFP in micellar or β-CD have been also determined. The thermodynamic parameters of formation of DMAFP:CD inclusion complex have been calculated from the temperature dependence of the fluorescence spectra of the formed complex. The highly negative value of formation entropy (ΔS = −98.0 J mol−1 K−1) reflects the high restrictions imposed on the movement of both the host and included guest molecules which is consistent with the increase of the fluorescence yield and blue shift of the fluorescence maximum.
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2013
This article reports modulation of intramolecular charge transfer (ICT) reaction of 2-methoxy-4-(N,Ndimethylamino)benzaldehyde (2-MDMABA) encapsulated within the cyclodextrin nanocavities investigated by steady state and time resolved measurements. The ICT emission, absent in bulk water, originates in the presence of a-, band c-CD with the huge enhancement of local emission. From the Benesi-Hildebrand plot, the stoichiometry of the host-guest inclusion complex is found to be 1:1 for band c-CD whereas 1:1 and 1:2 guest to host complexation occur at low and high concentration of a-CD, respectively. The association constants of the inclusion complexes have also been estimated from the Benesi-Hildebrand plot. The greater binding capability of 2-MDMABA with b-CD than that of other two CDs is further supplemented by time resolved study.