Three Distinct Equilibrium States via Self-Assembly: Simple Access to a Supramolecular Ion-Controlled NAND Logic Gate

During the past several decades, considerable effort has focused on self-assembled systems. However, most work has been directed toward understanding the equilibrium between two major chemical entities, namely the dissociated components and the corresponding associated complex. While there are quite a few examples of ‘multiresponsive’ materials, control over ‘multistate’ materials has proved difficult to achieve. Here, we report the formation and the interplay of a self-assembled calix[4]­pyrrole array that exhibits three limiting forms, namely a 1:1 self-assembled oligomer, a 2:1 capsule, and the corresponding monomers. Interconversion between these states may be controlled by using the tetraethylammonium cation (TEA⁺) and/or iodide anion (I^–) as chemical inputs. The combination of self-assembly and ion-based control may be used to create systems that display NAND logic behavior. The system outputs have been confirmed by a variety of analytic methods, including UV–vis and 2D ¹H DOSY, NOESY NMR spectroscopy, scanning electron microscopy, and single crystal X-ray diffraction analyses

Three Distinct Equilibrium States via Self-Assembly: Simple Access to a Supramolecular Ion-Controlled NAND Logic Gate

During the past several decades, considerable effort has focused on self-assembled systems. However, most work has been directed toward understanding the equilibrium between two major chemical entities, namely the dissociated components and the corresponding associated complex. While there are quite a few examples of ‘multiresponsive’ materials, control over ‘multistate’ materials has proved difficult to achieve. Here, we report the formation and the interplay of a self-assembled calix[4]­pyrrole array that exhibits three limiting forms, namely a 1:1 self-assembled oligomer, a 2:1 capsule, and the corresponding monomers. Interconversion between these states may be controlled by using the tetraethylammonium cation (TEA⁺) and/or iodide anion (I^–) as chemical inputs. The combination of self-assembly and ion-based control may be used to create systems that display NAND logic behavior. The system outputs have been confirmed by a variety of analytic methods, including UV–vis and 2D ¹H DOSY, NOESY NMR spectroscopy, scanning electron microscopy, and single crystal X-ray diffraction analyses

Three Distinct Equilibrium States via Self-Assembly: Simple Access to a Supramolecular Ion-Controlled NAND Logic Gate

During the past several decades, considerable effort has focused on self-assembled systems. However, most work has been directed toward understanding the equilibrium between two major chemical entities, namely the dissociated components and the corresponding associated complex. While there are quite a few examples of ‘multiresponsive’ materials, control over ‘multistate’ materials has proved difficult to achieve. Here, we report the formation and the interplay of a self-assembled calix[4]­pyrrole array that exhibits three limiting forms, namely a 1:1 self-assembled oligomer, a 2:1 capsule, and the corresponding monomers. Interconversion between these states may be controlled by using the tetraethylammonium cation (TEA⁺) and/or iodide anion (I^–) as chemical inputs. The combination of self-assembly and ion-based control may be used to create systems that display NAND logic behavior. The system outputs have been confirmed by a variety of analytic methods, including UV–vis and 2D ¹H DOSY, NOESY NMR spectroscopy, scanning electron microscopy, and single crystal X-ray diffraction analyses

Disparate Downstream Reactions Mediated by an Ionically Controlled Supramolecular Tristate Switch

The use of chemical messengers to control multiple and often disparate downstream events is a hallmark of biological signaling. Here, we report a synthetic supramolecular construct that gives rise to bifurcated downstream events mediated by different stimulus-induced chemical messengers. The system in question consists of a supramolecular redox-ensemble made up of a tetrathiafulvalene (TTF)-based macrocycle, benzo-TTF-calix[4]­pyrrole, and an electron deficient partner, 7,7,8,8-tetracyanoquinodimethane (TCNQ). Different tetraalkylammonium halide salts are used to trigger the reversible switching between neutral (No-ET), charge transfer (CT), and electron transfer (ET) states. The result is an effective tristate switch that provides chemical access to three different forms of TCNQ, namely, a released neutral, radical anionic (TCNQ^•–), or bound CT forms. The ionically induced switching chemistry is linked separately through the neutral and radical anion TCNQ forms to two distinct follow-on reactions. These reactions consist, respectively, of styrene polymerization, which is triggered only in the “1” (TCNQ radical anion ET) state, and a cycloaddition–retroelectrocyclization (CA–RE) reaction, which is mediated only by the neutral TCNQ “0” (No-ET) state. Neither downstream reaction is promoted by the CT form, wherein the TCNQ is receptor bound. The three states that characterize this system, their interconversion, and the downstream reactions promoted by TCNQ^•– and free TCNQ, respectively, have been characterized by single-crystal X-ray diffraction analyses and various solution phase spectroscopies

Disparate Downstream Reactions Mediated by an Ionically Controlled Supramolecular Tristate Switch

The use of chemical messengers to control multiple and often disparate downstream events is a hallmark of biological signaling. Here, we report a synthetic supramolecular construct that gives rise to bifurcated downstream events mediated by different stimulus-induced chemical messengers. The system in question consists of a supramolecular redox-ensemble made up of a tetrathiafulvalene (TTF)-based macrocycle, benzo-TTF-calix[4]­pyrrole, and an electron deficient partner, 7,7,8,8-tetracyanoquinodimethane (TCNQ). Different tetraalkylammonium halide salts are used to trigger the reversible switching between neutral (No-ET), charge transfer (CT), and electron transfer (ET) states. The result is an effective tristate switch that provides chemical access to three different forms of TCNQ, namely, a released neutral, radical anionic (TCNQ^•–), or bound CT forms. The ionically induced switching chemistry is linked separately through the neutral and radical anion TCNQ forms to two distinct follow-on reactions. These reactions consist, respectively, of styrene polymerization, which is triggered only in the “1” (TCNQ radical anion ET) state, and a cycloaddition–retroelectrocyclization (CA–RE) reaction, which is mediated only by the neutral TCNQ “0” (No-ET) state. Neither downstream reaction is promoted by the CT form, wherein the TCNQ is receptor bound. The three states that characterize this system, their interconversion, and the downstream reactions promoted by TCNQ^•– and free TCNQ, respectively, have been characterized by single-crystal X-ray diffraction analyses and various solution phase spectroscopies

Disparate Downstream Reactions Mediated by an Ionically Controlled Supramolecular Tristate Switch

The use of chemical messengers to control multiple and often disparate downstream events is a hallmark of biological signaling. Here, we report a synthetic supramolecular construct that gives rise to bifurcated downstream events mediated by different stimulus-induced chemical messengers. The system in question consists of a supramolecular redox-ensemble made up of a tetrathiafulvalene (TTF)-based macrocycle, benzo-TTF-calix[4]­pyrrole, and an electron deficient partner, 7,7,8,8-tetracyanoquinodimethane (TCNQ). Different tetraalkylammonium halide salts are used to trigger the reversible switching between neutral (No-ET), charge transfer (CT), and electron transfer (ET) states. The result is an effective tristate switch that provides chemical access to three different forms of TCNQ, namely, a released neutral, radical anionic (TCNQ^•–), or bound CT forms. The ionically induced switching chemistry is linked separately through the neutral and radical anion TCNQ forms to two distinct follow-on reactions. These reactions consist, respectively, of styrene polymerization, which is triggered only in the “1” (TCNQ radical anion ET) state, and a cycloaddition–retroelectrocyclization (CA–RE) reaction, which is mediated only by the neutral TCNQ “0” (No-ET) state. Neither downstream reaction is promoted by the CT form, wherein the TCNQ is receptor bound. The three states that characterize this system, their interconversion, and the downstream reactions promoted by TCNQ^•– and free TCNQ, respectively, have been characterized by single-crystal X-ray diffraction analyses and various solution phase spectroscopies

Disparate Downstream Reactions Mediated by an Ionically Controlled Supramolecular Tristate Switch

The use of chemical messengers to control multiple and often disparate downstream events is a hallmark of biological signaling. Here, we report a synthetic supramolecular construct that gives rise to bifurcated downstream events mediated by different stimulus-induced chemical messengers. The system in question consists of a supramolecular redox-ensemble made up of a tetrathiafulvalene (TTF)-based macrocycle, benzo-TTF-calix[4]­pyrrole, and an electron deficient partner, 7,7,8,8-tetracyanoquinodimethane (TCNQ). Different tetraalkylammonium halide salts are used to trigger the reversible switching between neutral (No-ET), charge transfer (CT), and electron transfer (ET) states. The result is an effective tristate switch that provides chemical access to three different forms of TCNQ, namely, a released neutral, radical anionic (TCNQ^•–), or bound CT forms. The ionically induced switching chemistry is linked separately through the neutral and radical anion TCNQ forms to two distinct follow-on reactions. These reactions consist, respectively, of styrene polymerization, which is triggered only in the “1” (TCNQ radical anion ET) state, and a cycloaddition–retroelectrocyclization (CA–RE) reaction, which is mediated only by the neutral TCNQ “0” (No-ET) state. Neither downstream reaction is promoted by the CT form, wherein the TCNQ is receptor bound. The three states that characterize this system, their interconversion, and the downstream reactions promoted by TCNQ^•– and free TCNQ, respectively, have been characterized by single-crystal X-ray diffraction analyses and various solution phase spectroscopies

Redox- and pH-Responsive Orthogonal Supramolecular Self-Assembly: An Ensemble Displaying Molecular Switching Characteristics

Two heteroditopic monomers, namely a thiopropyl-functionalized tetrathiafulvalene-annulated calix[4]­pyrrole (SPr-TTF-C[4]P <b>1</b>) and phenyl C₆₁ butyric acid (PCBA <b>2</b>), have been used to assemble a chemically and electrochemically responsive supramolecular ensemble. Addition of an organic base initiates self-assembly of the monomers via a molecular switching event. This results in the formation of materials that may be disaggregated via the addition of an organic acid or electrolysis

Modulation of Electronics and Thermal Stabilities of Photochromic Phosphino–Aminoazobenzene Derivatives in Weak-Link Approach Coordination Complexes

A series of d⁸ transition-metal (Pt­(II) and Pd­(II)) coordination complexes incorporating phosphine-functionalized aminoazobenzene derivatives as hemilabile phosphino–amine (P,N) ligands were synthesized and studied as model weak-link approach (WLA) photoresponsive constructs. The optical and photochemical properties of these complexes were found to be highly influenced by various tunable parameters in WLA systems, which include type of metal, coordination mode, type of ancillary ligand, solvent, and outer-sphere counteranions. In dichloromethane, reversible chelation and partial displacement of the P,N coordinating moieties allow for toggling between aminoazobenzene- or pseudostilbene- and azobenzene-type derivatives. The reversible switching between electronic states of azobenzene can be controlled through either addition or extraction of chloride counterions and is readily visualized in the separation between π–π* and n−π* bands in the complexes’ electronic spectra. In acetonitrile solution, the WLA variables inherent to semiopen complexes have a significant impact on the half-lives of the corresponding <i>cis</i> isomers, allowing one to tune their half-lives from 20 to 21000 s, while maintaining photoisomerization behaviors with visible light. Therefore, one can significantly increase the thermal stability of a <i>cis</i>-aminoazobenzene derivative to the extent that single crystals for X-ray diffraction analysis can be grown for the first time, uncovering an unprecedented edge-to-face arrangement of the phenyl rings in the <i>cis</i> isomer. Overall, the azobenzene-functionalized model complexes shed light on the design parameters relevant for photocontrolled WLA molecular switches, as well as offer new ways of tuning the properties of azobenzene-based, photoresponsive materials

Synthesis of 2‑Benzazepines from Benzylamines and MBH Adducts Under Rhodium(III) Catalysis via C(sp²)–H Functionalization

The rhodium­(III)-catalyzed cross-coupling reaction between commercially available benzylamines and Morita–Baylis–Hillman (MBH) adducts is described. This protocol provides a facile access to various 2-benzazepine derivatives via the C­(sp²)–H activation of <i>N</i>-allylated benzylamines and subsequent intramolecular olefin insertion followed by <i>N</i>-allylation reaction. A range of substrates has been used, and a high level of chemoselectivity as well as functional group tolerance was observed. To gain mechanistic insight of this transformation, DFT calculations were also performed