Organic cages with large cavities that support multiguest encapsulation and photocatalysis provide environmentally benign, sustainable platforms for regulating reactivity and exploring new multicomponent reactions for potentially bioactive molecule screening in drug discovery, but their rational construction remains challenging. Here, we use a novel macrocycle-to-cage strategy to construct a dodecacationic organic cage with a large cavity, framed by four 1,3,5-triazine-2,4,6-tris(pyridin-1-ium) sites, which can encapsulate two phenolic guests. This encapsulation-based confinement mediates unprecedented visible-light-driven multicomponent reactions of two phenolic substrates with one olefin, affording difunctionalized products containing bioactive moieties. Therefore, we establish a rational strategy for constructing large organic hosts that integrate multiguest encapsulation with visible-light-mediated catalysis, enabling previously inaccessible multicomponent reaction pathways and providing a route to rapidly populate libraries of potentially bioactive molecules.

As contact dimensions continue to shrink to support scaling, local CD variation (LCDU) becomes a critical driver of electrical variation and defectivity. Continued logic scaling is highly dependent on middle of line (MOL), which further amplifies the need for LCDU improvement. LCDU improvement will be critical to improving edge placement error (EPE). The same concepts can also be applied to back end of line (BEOL) vias. Since lithography tools are unable to consistently print contacts below 20 nm, it is typically necessary to shrink through etch. There are various etch techniques we can use to shrink contact dimensions each having different impacts on LCDU and defectivity. In this study we explore the impacts of various shrink methods to optimize LCDU and defect density. In this study a simple patterning stack of SiN + OPL + ARC + resist is used to simulate contact patterning. Various etch chambers and shrink techniques are used to reach a target CD range and LCDU and defect density are evaluated. The chambers evaluated include TEL's conductor etcher and TEL's dielectric etcher. LCDU data is collected using CDSEM. Defect density is evaluated using various etch techniques. Etch techniques such as deposition on resist, ARC and OPL, descum steps, pulsing and quasi atomic layer etch are explored. Multiple types of deposition techniques are used including selective deposition and cyclic deposition and trim. These techniques are optimized to be sensitive to open area and correct for local CD variations. On wafer LCDU performance of <2.0nm is demonstrated and further optimization is done to minimize defectivity.

Reported here is the synthesis, solid-state characterization, and redox properties of new triangular, threefold symmetric, viologen-containing macrocycles. Cyclotris(paraquat-p-phenylene) (CTPQT6+ ) and cyclotris(paraquat-p-1,4-dimethoxyphenylene) (MCTPQT6+ ) were prepared and their X-ray single-crystal (super)structures reveal intricate three-dimensional packing. MCTPQT6+ results in nanometer-sized channels, in contrast with its parent counterpart CTPQT6+ which crystallizes as a couple of polymorphs in the form of intercalated assemblies. In the solid state, MCTPQT3(.+) exhibits stacks between the 1,4-dimethoxyphenylene and bipyridinium radical cations, providing new opportunities for the manipulation and control of the recognition motif associated with viologen radical cations. These redox-active cyclophanes demonstrate that geometry-matching and weak intermolecular interactions are of paramount importance in dictating the formation of their intricate solid-state superstructures.

Self-Aligned Gate Contact (SAGC) integration is design based on formation of the two separate contacts to the source/drain (S/D) and to the gate (G), which are realized in two separate plasma etch steps. Essentially, the first one is the contact plug (CP) etch over S/D contact selective to the gate plug (GP) and sidewall spacer (SWS), and the second one is the gate plug (GP) etch selective to the contact plug (CP) and the sidewall spacer (SWS). Therefore, the high selectivity plasma etch processing for the CP and GP towards the other two relevant, neighboring films is a key requirement for successful SAGC integration. In this paper we present plasma etch process development required for SAGC implementation, primarily focusing on the multi-color selectivity studies, i.e., selective CP (towards GP and SWS) as well as selective GP (towards CP and SWS) at contacted poly pitch (CPP) 42nm. The primary ('standard') integration scheme uses SiO2 CP, Si3N4 GP and SiCO SWS. Furthermore, we investigate the " alternative' integration scheme with SiCxNy films as replacement of the traditionally used SiO2 CP material aiming to simplify the patterning sequence and ease high selectivity requirements. We report the selectivity values obtained on the CP/GP/SWS multi-color stack for the CP plasma processing (SiO2 or SiCxNy) towards Si3N4 and SiCO; as well as for GP (Si3N4) plasma dry etch process towards SiO2 or SiCxNy and SiCO. Using a Quasi-ALE (Q-ALE) approach for selective SiO2 etch process is developed with a selectivity of 8 to 1 towards Si3N4 and SiCO. For the selective Si3N4 etch continuous wave plasma CH3F-based process is developed and selectivity of 9 to 1 towards SiO2 and SiCO achieved. In the case of the integration scheme with SiCxNy CP, the selectivity for SiCxNy etch towards Si3N4 GP and SiCO SWS higher than 20 to 1 is accomplished using continuous RF source NF3/O-2-based process. As for the Si3N4 plasma etch in the 'alternative' scheme using CH3F/O-2-based process, the selectivity towards SiCxNy of higher than 20 to 1 and selectivity to SiCO of around 10 to1 is achieved.

The redox properties of cyclobis(paraquat- p-phenylene)cyclophane (CBPQT4+) render it a uniquely variable source of recognition in the context of mechanically interlocked molecules, through aromatic donor-acceptor interactions in its fully oxidized state (CPBQT4+) and radical-pairing interactions in its partially reduced state (CBPQT2(•+)). Although it is expected that the fully reduced neutral state (CBPQT(0)) might behave as a π-donating recognition unit, resulting in a dramatic change in its binding properties when compared with the other two redox states, its role in rotaxanes has not yet been investigated. To address this challenge, we report herein the synthesis of a tri-stable [2]rotaxane in which a CBPQT4+ ring is mechanically interlocked with a dumbbell component containing five recognition sites-(i) a bipyridinium radical cation (BIPY(•+)) located centrally along the axis of the dumbbell, straddled by (ii) two tetrafluorophenylene units linked to (iii) two triazole rings. In addition to the selective recognition between (iv) the CBPQT4+ ring and the triazole units, and (v) the CBPQT2(•+) ring and the reduced BIPY(•+) unit in the dumbbell component, investigations in solution have now confirmed the presence of additional non-covalent bonding interactions between the CBPQT(0) ring, acting as a donor in its neutral state, and the two tetrafluorophenylene acceptors in the dumbbell component. The unveiling of this piece of molecular recognition in a [2]rotaxane is reminiscent of the existence in much simpler, covalently linked, organic molecules of neighboring group participation (anchimeric assistance giving way to transannular interactions) in small-, medium-, and large-membered rings.

Two potential radical promoted molecular lassos were synthesized, and their different behaviour under redox stimuli shows how the molecular-level properties of analogous compounds can be affected drastically by subtle structural differences.

Radical templation centered around a heterotrisradical tricationic inclusion complex DB•+⊂DAPQT2(•+), assembled from an equimolar mixture of a disubstituted 4,4'-bipyridinium radical cation (DB•+) and an asymmetric cyclophane bisradical dication (DAPQT2(•+)), affords a symmetric [2]catenane (SC·7PF6) and an asymmetric [2]catenane (AC·7PF6) on reaction of the 1:1 complex with diazapyrene and bipyridine, respectively. Both these highly charged [2]catenanes have been isolated as air-stable monoradicals and characterized by EPR spectroscopy. X-ray crystallography suggests that the unpaired electrons are delocalized in each case across two inner 4,4'-bipyridinium (BIPY2+) units forming a mixed-valence (BIPY2)•3+ state inside both [2]catenanes, an observation which is in good agreement with spin-density calculations using density functional theory. Electrochemical studies indicate that by replacing the BIPY2+ units in homo[2]catenane HC•7+-composed of two mechanically interlocked cyclobis(paraquat-p-phenylene) rings-with "zero", one, and two more highly conjugated diazapyrenium dication (DAP2+) units, respectively, a consecutive series of five, six, and seven redox states can be accessed in the resulting SC·7PF6 (0, 4+, 6+, 7+, and 8+), HC·7PF6 (0, 2+, 4+, 6+, 7+, and 8+), and AC·7PF6 (0, 1+, 2+, 4+, 6+, 7+, and 8+), respectively. These unique [2]catenanes present a promising prototype for the fabrication of high-density data memories.

A strategy for creating foldameric oligorotaxanes composed of only positively charged components is reported. Threadlike components-namely oligoviologens-in which different numbers of 4,4'-bipyridinium (BIPY(2+)) subunits are linked by p-xylylene bridges, are shown to be capable of being threaded by cyclobis(paraquat-p-phenylene) (CBPQT(4+)) rings following the introduction of radical-pairing interactions under reducing conditions. UV/vis/NIR spectroscopic and electrochemical investigations suggest that the reduced oligopseudorotaxanes fold into highly ordered secondary structures as a result of the formation of BIPY(•+) radical cation pairs. Furthermore, by installing bulky stoppers at each end of the oligopseudorotaxanes by means of Cu-free alkyne-azide cycloadditions, their analogous oligorotaxanes, which retain the same stoichiometries as their progenitors, can be prepared. Solution-state studies of the oligorotaxanes indicate that their mechanically interlocked structures lead to the enforced interactions between the dumbbell and ring components, allowing them to fold (contract) in their reduced states and unfold (expand) in their fully oxidized states as a result of Coulombic repulsions. This electrochemically controlled reversible folding and unfolding process, during which the oligorotaxanes experience length contractions and expansions, is reminiscent of the mechanisms of actuation associated with muscle fibers.

We describe the incorporation of a bistable mechanically interlocked molecule (MIM) into a robust Zr-based metal-organic framework (MOF), NU-1000, by employing a post-synthetic functionalization protocol. On average, close to two bistable [2]catenanes can be incorporated per repeating unit of the hexagonal channels of NU-1000. The reversible redox-switching of the bistable [2]catenanes is retained inside the MOF, as evidenced by solid-state UV-vis-NIR reflectance spectroscopy and cyclic voltammetry. This research demonstrates that bistable MIMs are capable of exhibiting robust dynamics inside the nanopores of a MOF.

When equimolar solutions of the enantiomeric naphthalenediimide-based highly rigid triangles R-Δ and S-Δ in ClCH2CH2Cl are mixed, the racemate rac-Δ forms an organogel that is composed of interwoven fibers, resulting from the columnar stacking of the triangles in an alternating R-Δ/S-Δ fashion. Under identical conditions, the pure enantiomers do not form organogels. Density functional theory calculations reveal that the racemic RS dimer is more stable than the RR dimer as a result of the enantiomeric relationship between R-Δ and S-Δ, allowing them to act as two complementary rings comprised of 12 [C-H···O] interactions with an unprecedented and uninterrupted circular ADDAADDAADDA·DAADDAADDAAD alignment of hydrogen bond donors (D) and acceptors (A), in contrast with the square-wave manner in which the RR dimer forms a complementary yet interrupted ADADAD·DADADA circular sequence of six longer [C-H···O] hydrogen bonds. It follows that gelation is favored by weak interactions acting cooperatively in rings under precise stereoelectronic control.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Herein, we report an alkali metal cation-dependent approach to gold recovery, facilitated by second-sphere coordination with eco-friendly α-cyclodextrin (α-CD). Upon mixing eight salts composed of Na(+), K(+), Rb(+), or Cs(+) cations and [AuX4](-) (X = Cl/Br) anions with α-, β-, or γ-CD in water, co-precipitates form selectively from the three (out of 24) aqueous solutions containing α-CD with KAuBr4, RbAuBr4, and CsAuBr4, from which the combination of α-CD and KAuBr4 affords the highest yield. Single-crystal X-ray analyses reveal that in 20 of the 24 adducts CD and [AuX4](-) anions form 2:1 sandwich-type second-sphere adducts driven partially by [C-H···X-Au] interactions between [AuX4](-) anions and the primary faces of two neighboring CDs. In the adduct formed between α-CD and KAuBr4, a [K(OH2)6](+) cation is encapsulated inside the cavity between the secondary faces of two α-CDs, leading to highly efficient precipitation owing to the formation of a cation/anion alternating ion wire residing inside a continuous α-CD nanotube. By contrast, in the other 19 adducts, the cations are coordinated by OH groups and glucopyranosyl ring O atoms in CDs. The strong coordination of Rb(+) and Cs(+) cations by these ligands, in conjunction with the stereoelectronically favorable binding of [AuBr4](-) anions with two α-CDs, facilitates the co-precipitation of the two adducts formed between α-CD with RbAuBr4 and CsAuBr4. In order to develop an efficient process for green gold recovery, the co-precipitation yield of α-CD and KAuBr4 has been optimized regarding both the temperature and the molar ratio of α-CD to KAuBr4.

Since the advent of mechanically interlocked molecules (MIMs), many approaches to templating their formation using various different noncovalent bonding interactions have been introduced and explored. In particular, employing radical-pairing interactions between BIPY(.+) units, the radical cationic state of 4,4'-bipyridinium (BIPY(2+) ) units, in syntheses is not only a convenient but also an attractive source of templation because of the unique properties residing in the resulting catenanes and rotaxanes. Herein, we report a copper-mediated procedure that enables the generation, in the MIM-precursors, of BIPY(.+) radical cations, while the metal itself, which is oxidized to Cu(I) , catalyzes the azide-alkyne cycloaddition reactions that result in the efficient syntheses of two catenanes and one rotaxane, assisted by radical-pairing interactions between the BIPY(.+) radical cations. This procedure not only provides a fillip for making and investigating the properties of Coulombically challenged catenanes and rotaxanes, but it also opens up the possibility of synthesizing artificial molecular machines which operate away from equilibrium.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.