Kiilerichbuch8461
Consequently, taking advantage of the multiresponsive dynamic wrinkling/ordered patterning, we can program globally 2D ordered surface patterns with diverse morphologies on demand and manipulate the resulted surface properties as desired.Synthetic macroscopic materials transforming from bulk solid or semisolid to a closed structure with inner cavities and distinct outer and inner microstructures are rarely reported. Here, we report an in situ method for directing spatial surface-interior separation from bulk dynamic hydrogels to closed three-dimensional (3D) hydrogel containers with inner cavities via constructing a competitively cross-linking gradient within dynamic hydrogels. The initial cross-linking of phenylboronic acid/catechol complexes is disrupted by stronger ferric ions/catechol associations, generating gradually weakened cross-linking from the outside to the inside. Both stronger cross-linking in the outer shells and sequentially weaker cross-linked interior generated during swelling closed the hydrogel container with a tunable dense outer shell, fluffy inner layer, and cavities in the core. Cellulose nanocrystals could be used to significantly improve the spatial distinction of gradient cross-linking within hydrogels, leading to an even denser outer shell with tunable shell thickness. Moreover, cavitary hydrogel containers with diverse shapes can be programmed by designing the initial shapes of dynamic hydrogels and macroscopic assembly of individual dynamic hydrogels based on their self-healing capability after subsequent surface-interior separation. These cavitary hydrogel containers demonstrate thermal-responsive gate systems with unique sustained release at higher temperature and potential reaction containers for oxygen generation on demand. This facile spatial surface-interior separation strategy for fabricating closed cavity systems has great potential for various applications.A series of electron donor-acceptor compounds are reported in which both the donor and acceptor strengths are systematically altered using mono-, bi-, and terthiophene as donors and benzo[c][1,2,5]thiadiazole (btd), dipyrido[3,2-a2',3'-c]phenazine (dppz), and the corresponding rhenium(I) complex, [ReCl(CO)3(dppz)], as acceptors. The electronic properties of the compounds are characterized using electrochemistry, electronic absorbance and emission spectroscopies, and transient absorption spectroscopy. The effect of donor and acceptor strengths on frontier molecular orbital localization and on the charge-transfer (CT) character of optical transitions is modeled using density functional theory (DFT) calculations. The electronic absorption spectra of the compounds investigated are dominated by intraligand charge-transfer (ILCT) transitions, where the CT character is shown to increase across the series from mono- to bi- to terthiophene but not significantly across the acceptor series. Emission is shown to originate from the absorbing state. Long-lived nonemissive states have been observed using transient absorption spectroscopy and assigned using triplet-state DFT calculations, which indicate that the lowest energy excited state has more thiophene-localized π,π* character with an increasing number of appended thiophenes.A detailed correlation between topographical features and wettability of chemically modified coatings based on silica nanoparticles (SiO2) was performed. In this study, hierarchical structures were prepared by the layer-by-layer (LbL) technique using two different approaches random roughened surfaces were obtained by exploring stacking defects spontaneously arisen after 15, 30, and 45 assembly cycles of 22 nm SiO2, and a particular structure, commonly known as raspberry-like, was obtained by depositing 22 nm SiO2 over the first deposited 400 nm SiO2. Selleck Sunitinib As an intrinsic attribute of the assembly process, the average slope of random roughened surfaces seems to be constant and virtually independent of the number of deposited layers. Additionally, the local slopes are always lower than a critical value (Φcrit) required to stabilize the solid-liquid-air interface; thus, a fully wetted Wenzel state is invariably observed with water contact angles (WCAs) ∼130°. On the other hand, since the local slopes of the raspberry-like structure follow a nearly spherical curvature, small SiO2 can stabilize the solid-liquid-air interface by increasing the local contact angle and avoid the deep penetration of water into the surface asperities, resulting in a WCA ∼167°. The results also suggest that nanoroughness might also play an important role in the pinning effect of the solid-liquid-air contact line, favoring the maintenance of superhydrophobicity of raspberry-like surfaces.The [2+2] cyclcoaddition (CA) and subsequent retroelectrocyclization (RE) reactions are useful in constructing nonplanar donor-acceptor chromophores that exhibit nonlinear optical properties and intramolecular charge-transfer transitions. However, both the infrared (IR) and visible-near IR (vis-NIR) spectroelectrochemical responses of CA-RE-derived chromophores are rarely explored in depth. Reported in this contribution is a comprehensive IR and vis-NIR spectroelectrochemical study of the CA-RE adducts of DMAP-C2n-NAPiPr of both tetracyanoethene (TCNE) and tetracyanoquinodimethane (TCNQ) and companion time-dependent density functional theory (TD-DFT) analysis of the bands observed. Specifically, DMAP-C2n-NAPiPr (1a, n = 1; 1bn = 2; DMAP = N,N-dimethylaniline; NAPiPr = N-isopropyl-1,8-naphthalimide) react with TCNE to yield the tetracyanobutadiene (TCBD) derivatives (2a and 2b, respectively) and with TCNQ to yield the dicyanoquinodimethane (DCNQ) derivatives (3a and 3b, respectively). IR spectroelectrochemical studies showed the emergence/intensification of new CN stretches upon reductions. Ultraviolet-vis-NIR (UV-vis-NIR) spectroelectrochemical study of 3 revealed a partial bleach of the charge-transfer (CT) bands, originally appearing in the neutral species, and the emergence of new CT bands originating from NAPiPr to the reduced DCNQ moiety. UV-vis-NIR spectroelectrochemical study of 2, surprisingly, indicated a very minimal change upon reductions. Dynamic changes were observed in the mid-IR absorption for C≡C and C≡N for both 2 and 3, indicative of enhanced asymmetry and the formation of ion pairs on the dicyano bridge. DFT and TD-DFT analyses were used to obtain the semi-quantitative pictures of the frontier orbitals of 1-3 and elucidate the origin of the transient features observed spectroelectrochemically for the 1e- and 2e- reduced species.