3 research outputs found
Third-Order Nonlinear Optical Properties of Endohedral Fullerene (H<sub>2</sub>)<sub>2</sub>@C<sub>70</sub> and (H<sub>2</sub>O)<sub>2</sub>@C<sub>70</sub> Accompanied by the Prospective of Novel (HF)<sub>2</sub>@C<sub>70</sub>
In view of the experimental
observation of (H<sub>2</sub>)<sub>2</sub>@C<sub>70</sub> and (H<sub>2</sub>O)<sub>2</sub>@C<sub>70</sub>, it has been suggested that
hydrogen fluoride (HF) dimer can be
completely localized within the sub-nanospace inside the fullerene
C<sub>70</sub> cage. With the aim of quantum chemical prospective
of (HF)<sub>2</sub>@C<sub>70</sub>, electronic structure calculations
of C<sub>60</sub> hosting H<sub>2</sub>, HF, and H<sub>2</sub>O monomers,
as well as C<sub>70</sub> hosting H<sub>2</sub>, HF, and H<sub>2</sub>O monomers and dimers, were performed by using the density functional
theory, together with the quantum theory of atoms in molecules, the
natural population, and interaction energy calculation. The F–H···F
bonding energy inside C<sub>70</sub> was estimated at −13.25
kcal/mol, which is smaller than that of free dimer in the gas phase
(−8.37 kcal/mol). Exploration of various featured properties
suggests that (HF)<sub>2</sub>@C<sub>70</sub> may be also regarded
as a unique system composed of both inter- and intramolecular interactions
like (H<sub>2</sub>)<sub>2</sub>@C<sub>70</sub> and (H<sub>2</sub>O)<sub>2</sub>@C<sub>70</sub>. In addition, absorption spectroscopy
and linear and nonlinear optical coefficients of C<sub>60</sub> hosting
H<sub>2</sub>, HF, and H<sub>2</sub>O monomers, as well as C<sub>70</sub> hosting H<sub>2</sub>, HF, and H<sub>2</sub>O monomers and dimers,
have also been forecasted. The results show that there is almost no
influence of embedded H<sub>2</sub>, HF, and H<sub>2</sub>O monomers
and dimers on the peak wavelength of absorption spectra for C<sub>60</sub> and C<sub>70</sub>. Endohedral C<sub>70</sub> possesses
the larger second hyperpolarizabilities with respect to that of endohedral
C<sub>60</sub>, indicating that the effect of cage size is effective
in the second hyperpolarizabilities of endohedral fullerenes. The
study will benefit not only the designation and the syntheses of the
novel molecular (HF)<sub>2</sub>@C<sub>70</sub> but also the understanding
of the structures and properties of endohedral fullerenes
Self-Assembled Donor–Acceptor Chromophores: Evident Layer Effect on the First Hyperpolarizability and Two-Dimensional Charge Transfer Character
Self-assembled
donor–acceptor chromophores have extensive
applications in photofunctional devices owing to their unique charge
transport properties. To explore the possibility of improving nonlinear
optical (NLO) properties by self-assembly to multilayer complexes,
we theoretically investigated the geometric and electronic structures,
interlayer weak interactions, absorption spectra, charge transfer
properties, polarizabilities (α), and first hyperpolarizabilities
(β) of naphthalimide, -phenyl, and -naphthyl monomers, dimers,
and trimers by increasing the layer number <i>n</i> (<i>n</i> = 1, 2, 3). Different stacking patterns of their dimers
were also taken into account. These show that parallel stacking patterns
are conducive to maximizing overlap with respect to antiparallel ones
due to the concept of optimal π-orbital overlap is more vast
than purely maximizing cofacial overlap to improve charge transport.
The decreases in band gap for the di/trimeric versus monomeric naphthalimide,
-phenyl, and -naphthyl monomers indicate the possibility of more favorable
photoinduced electron transition in the aggregate when compared to
the monomer. The linear and second-order NLO properties of these complexes
are investigated in detail. The α values increase linearly as
the increased number <i>n</i> of the layer (<i>n</i> = 1, 2, and 3), providing a new kind of tendency forecast method
for the linear optical properties. Along with the increasing electron
donating ability of the donor, the β<sub>tot</sub> values of
monomers increased, revealing the general rule of designing NLO molecular
materials. The dependence of β<sub>tot</sub> value on the layer
number shows that the β<sub>tot</sub> value increased with the
increased number of layer, which can be rationalized by considering
the enhancement of interlayer electronic transition and two-dimensional
NLO character with the two charge transfer axes. We hope this work
may evoke one’s attention to design new, highly efficient second-order
NLO materials with excellent building blocks: multilayer complexes
Second-Order Nonlinear Optical Properties of Carboranylated Square-Planar Pt(II) Zwitterionic Complexes: One-/Two-Dimensional Difference and Substituent Effect
Zwitterionic
complexes have been the subject of great interest
in the past several decades due to their multifunctional application
in supramolecular chemistry. Herein, a series of internally stable
charge-compensated carboranylated square-planar PtÂ(II) zwitterionic
complexes have been explored by density functional theory aim to assessing
their structures, the first hyperpolarizabilities, first hyperpolarizability
densities, and electronic absorption spectra. It is found that the
first hyperpolarizabilities of two-dimensional (2D) structure complexes
are much larger with respect to the one-dimensional complex. It is
ascribed to the lower transition energy and more obvious charge transfer,
which can be further illustrated by their large amplitude and separate
distribution of first hyperpolarizability density. In addition, the
first hyperpolarizabilities of 2D complexes can be further significantly
modified by introducing electron-donating/withdrawing groups on the
carborane cage. As a consequence, we believe that these 2D zwitterionic
complexes can behave as novel second-order nonlinear optical chromophore
with a promising future