Due to their unique structural, physical and chemical properties, cyclodextrins and their derivatives have been of great interest to scientists and researchers in both academia and industry for over a century. Many of the industrial applications of cyclodextrins have arisen from their ability to encapsulate, either partially or fully, other molecules, especially organic compounds. Cyclodextrins are non-toxic oligopolymers of glucose that help to increase the solubility of organic compounds with poor aqueous solubility, can mask odors from foul-smelling compounds, and have been widely studied in the area of drug delivery. In this review, we explore the structural and chemical properties of cyclodextrins that give rise to this encapsulation (i.e., the formation of inclusion complexes) ability. This review is unique from others written on this subject because it provides powerful insights into factors that affect cyclodextrin encapsulation. It also examines these insights in great detail. Later, we provide an overview of some industrial applications of cyclodextrins, while emphasizing the role of encapsulation in these applications. We strongly believe that cyclodextrins will continue to garner interest from scientists for many years to come, and that novel applications of cyclodextrins have yet to be discovered.

Controlling charge transfer (CT), charge separation (CS), and charge recombination (CR) at the donor–acceptor interface is extremely important to optimize the conversion efficiency in solar cell devices. In general, ultrafast CT and slow CR are desirable for optimal device performance. In this Letter, the ultrafast excited-state CT between platinum oligomer (DPP-Pt­(acac)) as a new electron donor and porphyrin as an electron acceptor is monitored for the first time using femtosecond (fs) transient absorption (TA) spectroscopy with broad-band capability and 120 fs temporal resolution. Turning the CT on/off has been shown to be possible either by switching from an organometallic oligomer to a metal-free oligomer or by controlling the charge density on the nitrogen atom of the porphyrin meso unit. Our time-resolved data show that the CT and CS between DPP-Pt­(acac) and cationic porphyrin are ultrafast (approximately 1.5 ps), and the CR is slow (ns time scale), as inferred from the formation and the decay of the cationic and anionic species. We also found that the metallic center in the DPP-Pt­(acac) oligomer and the positive charge on the porphyrin are the keys to switching on/off the ultrafast CT process.

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Summary Solution casting and ultrasonic‐assisted solution‐cast methods were used to create polymer nanocomposites films based on polyvinyl alcohol (PVA)/polyvinyl pyrrolidone (PVP) filled with varying concentrations of BaTiO3 nanoparticles. The X‐ray diffraction (XRD), Fourier‐transform infrared (FT‐IR), transmission electron microscope, and differential scanning calorimetry (DSC) were used to study the properties of the produced polymer nanocomposite samples. The properties of PVA/PVP‐BaTiO3 nanocomposites, such as ac conductivity, dielectric constant, and dielectric loss, were investigated as a function of BaTiO3 concentration. XRD measurements demonstrate that the pure polymer blend is semi‐crystalline and that the crystallinity degree (Xc) of the doped PVA/PVP mix films is lower than that of the pure blend. Significant variations in the FT‐IR spectra demonstrate the interaction between the BaTiO3 ions and the PVA/PVP matrix. The DSC analysis demonstrates that the PVA/PVP has a single glass transition temperature (Tg), showing that the two polymers are miscible. In addition, when the amount of BaTiO3 NP's increased, the Tg of the nanocomposite films decreased. The AC conductivity spectra of all samples obey Jonscher's power law. For a better understanding of charge storage characteristics and conductivity relaxation, dielectric constant and loss investigations have been carried out. The PVA/PVP mixed with 1.5 wt% BaTiO3 nanofiller achieves a maximum ionic conductivity of ~8.57 × 10−5 S/cm. In this investigation, which introduced a novel approach, the complex permittivity revealed that the real part value of the dielectric constant (ε′) for all samples was much bigger than the imaginary part (ε″) value. These results are predicted to have a significant influence on a variety of applications, including polymer organic semiconductors, energy storage, polymer solar cells, and nanoelectronics.

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We report how electrostatic interactions significantly impact charge transfer at CdTe QDs/fullerene interfaces.

Singlet-to-triplet intersystem crossing (ISC) and photoinduced electron transfer (PET) of platinum(II)-containing diketopyrrolopyrrole (DPP) oligomers in the presence and absence of tetracyanoethylene (TCNE), a strong electron-acceptor, were investigated using femtosecond and nanosecond transient absorption spectroscopy with broadband capabilities. The effect of incorporating platinum(II) in the photophysical properties of DPP molecule was evaluated by comparing the excited-state dynamics of DPP with and without Pt metal centers. Steady-state measurements reveal that platinum(II) incorporation greatly facilitates interactions between DPP-Pt(acac) and TCNE, resulting in the formation of charge transfer (CT) complexes. In the absence of TCNE, the transient absorption spectra revealed ultrafast ISC of DPP-Pt(acac) followed by a long-lived triplet state; however, in the presence of TCNE, PET from the excited DPP-Pt(acac) and from DPP to TCNE formed radical ion pairs. We measured an ultrafast PET from DPP-Pt(acac) to TCNE (i.e., a picosecond regime) that was much faster than that from DPP to TCNE (i.e., nanosecond time scale), which is a diffusion-controlled process. Our results provide clear evidence that the PET rate is eventually controlled by the platinum(II) incorporation.

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