An anionic surfactant (SDS) modulates the photoluminescence of graphene oxide (GO) in both acidic and alkaline medium. In the acidic medium (pH z 2), formation of hemi spherical surface micelles on the GO sheets creates a non-polar environment around the flourophoric moiety of GO and hinders the solvent relaxation. This leads to a significant 36 nm blue shift of the photoluminescence band, whereas in alkaline medium (pH z 10), SDS interacts with GO sheets in a different way due to the presence of negatively charged carboxylate ions at the GO edges. The repulsion between the negatively charged GO sheets and the intercalation of SDS within the basal planes of GO may weaken p-p stacking interaction which produces largely separate layers of GO. The largely separated GO sheets due to very weak stacking interactions among successive layers may behave almost like isolated functionalized GO, resulting in an enhancement of the photoluminescence intensity at 303 nm.
Reaction pathways involved in catalytic Cross Dehydrogenative Coupling (CDC) reactions leading to formation of Si−O and Si−S bonds have been formulated and explored theoretically using Density Functional Theory (DFT). The advantage of the weak Si−H bond has been exploited to carry out coupling with water, alcohol and thiol, along with H2 release. Ru complex, [K(dme)2][Ru(H)(trop2dad)] when reacts with water generates a neutral complex, [Ru(trop2dad)]. This neutral complex has been employed to act as a catalyst in CDC reactions. It has also been found that the complex, [Ru(H2)(trop2dad)] formed within the catalytic cycle may also be used for hydrogenation of C=O, C=N and N=N bonds. The optimized geometries of all the complexes and transition states have been obtained using wB97xd functional in conjunction with 6‐31++G(d,p) basis set. The whole assisting phenomena in solvent medium has been investigated through the implementation of conductor‐like screening solvation model (COSMO) considering tetrahydrofuran as the bulk solvent medium. The Turnover frequency (TOF) has been calculated by Energetic Span Model. The theoretical investigation extends the role of the ruthenium catalyst to the regime of ‘element to element’ bond formation, along with H2 release, which may be significant in the field of energy storage, and also triggers an alternative possibility of hydrogenation of carbonyls, imines and diazo compounds.
Diels-Alder cycloaddition reaction is helpful to produce covalent
derivatives of fullerene with desirable electronic and physical
properties. In the present venture, we have computationally investigated
the reactivity of neutral C and its
Li encapsulated derivative towards Multi-Diels-Alder
(MDA) reaction with 1,3-butadiene, employing density functional theory
(DFT). The computational reports available to date illustrate the
functionalization of fullerene surfaces of neutral and encapsulated
C (Ca and Sm) with two butadiene molecules. In this
article, we aim to investigate whether more than two butadiene molecules
can be attached to the fullerene surface or not. To do so, we have shown
that the MDA reaction initiates with the formation of an encounter
complex between the mono-functionalized fullerene product and the second
butadiene molecule. In this context, two different approaches, namely
‘Direct’ and ‘Alternative’ have been considered based on the attachment
of the second butadiene, i.e., whether it is attached to the opposite or
adjacent position of the first functionalization, which eventually
produces the same final product. We have explored the MDA reactions by
considering a total of four diene molecules that can be embedded
successfully on the fullerene surface, with each reaction step having a
high degree of exothermicity, thus making the overall reaction
thermodynamically facile. In harmony with the mono- and
bis-cycloaddition reactions, for MDA reaction also, the positive impact
of Li encapsulation for enhancing the reactivity of
fullerene surface towards butadiene attachment is evident from our
study. On-the-fly calculations also suggest the bond preference for
[6, 6] connectivity than its [6, 5] counterpart, to be the
suitable dienophile, just like the mono- and bis-functionalization
reported earlier. Overall, the present study will foresee an extensive
idea about the detailed mechanism of the MDA reaction on neutral
C and Li@C that
could encourage the scientists to perform the aforementioned reaction
for other fullerene derivatives in the long run.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.