Enzymatic Reaction-Coupled, Cooperative Supramolecular Polymerization.

Nature employs sophisticated mechanisms to precisely regulate self-assembly and functions within biological systems, exemplified by the formation of cytoskeletal filaments. Various enzymatic reactions and auxiliary proteins couple with the self-assembly process, meticulously regulating the length and functions of resulting macromolecular structures. In this context, we present a bioinspired, reaction-coupled approach for the controlled supramolecular polymerization in synthetic systems. To achieve this, we employ an enzymatic reaction that interfaces with the adenosine triphosphate (ATP)-templated supramolecular polymerization of naphthalene diimide monomers (NSG). Notably, the enzymatic production of ATP (template) plays a pivotal role in facilitating reaction-controlled, cooperative growth of the NSG monomers. This growth process, in turn, provides positive feedback to the enzymatic production of ATP, creating an ideal reaction-coupled assembly process. The success of this approach is further evident in the living-growth characteristic observed during seeding experiments, marking this method as the pioneering instance where reaction-coupled self-assembly precisely controls the growth kinetics and structural aspects of supramolecular polymers in a predictive manner, akin to biological systems.

Chiroptical Amplification of Induced Circularly Polarized Luminescence in Nucleotide-Templated Supramolecular Polymer.

Efficient circularly polarized luminescence (CPL) from purely organic molecules holds great promise for applications in displays, sensing, and bioimaging. However, achieving high dissymmetry values (glum ) from organic chromophores remains a significant challenge. Herein, we present a bioinspired approach using adenosine triphosphate (ATP)-triggered supramolecular polymerization of a naphthalene diimide-derived monomer (ANSG) to induce CPL with a remarkable glum value of 1.1×10-2 . The ANSG molecules undergo a templated, chiral self-assembly through a cooperative growth mechanism in the presence of ATP, resulting in scrolled nanotubes with aggregation-induced enhanced emission (AIEE) and induced CPL. Furthermore, we demonstrate the concept of chiroptical amplification of induced CPL by efficiently amplifying asymmetry using a mixture of chiral ATP and achiral pyrophosphate. This innovative approach opens numerous opportunities in the emerging field of circularly polarized luminescence.

ATP-Driven Synthetic Supramolecular Assemblies: From ATP as a Template to Fuel.

Adenosine triphosphate (ATP) is a molecular unit of energy that drives various processes in the cellular environment. In this Minireview, we discuss the potential of physical and chemical properties of ATP for the development of bio-inspired, synthetic ATP-induced supramolecular systems with dynamic, stimuli-responsive and active assembly characteristics. Molecular design rules for ATP-induced assemblies with various architectures and their stimuli-responsive structural and functional response are categorized. Special attention is given to the immense potential of ATP-fuelled designs in the nascent field of transient/non-equilibrium supramolecular polymerization for the synthesis of lifelike temporally programmable soft materials. Finally, the existing dearth and fate of ATP-driven systems for future challenges are discussed.

Bioinspired, ATP-driven co-operative supramolecular polymerization and its pathway dependence.

A bio-inspired, ATP-driven nucleation growth assembly is demonstrated using an amphiphilic naphthalene diimide (NDI) derivative appended with guanidinium receptors to promote specific salt-bridge type interaction with nucleotide phosphates. Detailed spectroscopic and microscopic probing revealed a pathway-dependent co-operative self-assembly to yield two-dimensional and scrolled nano-tubular bilayer assemblies under kinetic and thermodynamic conditions, respectively.

Biomimetic temporal self-assembly via fuel-driven controlled supramolecular polymerization.

Temporal control of supramolecular assemblies to modulate the structural and transient characteristics of synthetic nanostructures is an active field of research within supramolecular chemistry. Molecular designs to attain temporal control have often taken inspiration from biological assemblies. One such assembly in Nature which has been studied extensively, for its well-defined structure and programmable self-assembly, is the ATP-driven seeded self-assembly of actin. Here we show, in a synthetic manifestation of actin self-assembly, an ATP-selective and ATP-fuelled, controlled supramolecular polymerization of a phosphate receptor functionalised monomer. It undergoes fuel-driven nucleation and seeded growth that provide length control and narrow dispersity of the resultant assemblies. Furthermore, coupling via ATP-hydrolysing enzymes yielded its transient characteristics. These results will usher investigations into synthetic analogues of important biological self-assembly motifs and will prove to be a significant advancement toward biomimetic temporally programmed materials.

Adenosine-Phosphate-Fueled, Temporally Programmed Supramolecular Polymers with Multiple Transient States.

Natural systems have been an inspiration to synthetic supramolecular chemistry. Synthetic demonstrations of dissipative biological systems such as actin filaments are a formidable scientific challenge in attaining future life-like materials. Dynamic instability of such structures beckons control of self-organization in the temporal regimes. In this study, we present a fuel-dependent helical assembly of a supramolecular polymer. We further attempt the synthetic manifestation of a temporally programmable self-assembly. Additionally, the fuel-induced chiral (re)organization with the employment of various enzymes singularly and in tandem have resulted in designing a multistate transient self-assembly. These parameter modulations result in controllable lifetimes and rates. We thus report, for the first time, a temporally programmed multistate reorganization of self-assembly.

A dynamic supramolecular polymer with stimuli-responsive handedness for in situ probing of enzymatic ATP hydrolysis.

Design of artificial systems, which can respond to fluctuations in concentration of adenosine phosphates (APs), can be useful in understanding various biological processes. Helical assemblies of chromophores, which dynamically respond to such changes, can provide real-time chiroptical readout of various chemical transformations. Towards this concept, here we present a supramolecular helix of achiral chromophores, which shows chiral APs responsive tunable handedness along with dynamically switchable helicity. This system, composing of naphthalenediimides with phosphate recognition unit, shows opposite handedness on binding with ATP compared with ADP or AMP, which is comprehensively analysed with molecular dynamic simulations. Such differential signalling along with stimuli-dependent fast stereomutations have been capitalized to probe the reaction kinetics of enzymatic ATP hydrolysis. Detailed chiroptical analyses provide mechanistic insights into the enzymatic hydrolysis and various intermediate steps. Thus, a unique dynamic helical assembly to monitor the real-time reaction processes via its stimuli-responsive chiroptical signalling is conceptualized.

Supramolecular clippers for controlling photophysical processes through preorganized chromophores.

A novel supramolecular clipping design for influencing the photophysical properties of functional molecular assemblies, by the preorganization (clipping) of chromophores, is described. Several chromophores end functionalized with molecular recognition units were designed. These molecular recognition units serve as handles to appropriately position these systems upon noncovalent interactions with multivalent guest molecules (supramolecular clippers). Towards this goal, we have synthesized 1,5-dialkoxynaphthalene (DAN) and naphthalenediimide (NDI) functionalized with dipicolylethylenediamine (DPA) motifs. These molecules could preorganize upon noncovalent clipping with adenosine di- or triphosphates, which resulted in preassociated excimers and mixed (cofacial) charge-transfer (CT) assemblies. Chiral guest binding could also induce supramolecular chirality, not only into the individual chromophoric assembly but also into the heteromeric CT organization, as seen from the strong circular dichroism (CD) signal of the CT transition. The unique ability of this design to influence the intermolecular interactions by changing the binding strength of the clippers furthermore makes it very attractive for controlling the bimolecular photophysical processes.

Shape assisted fabrication of fluorescent cages of squarate based metal-organic coordination frameworks.

Micronic cage structures of squarate based metal-organic coordination frameworks (MOCFs) have been fabricated for the first time by specific anion selective etching of metal squarate cubes. Time and stoichiometry dependent synthesis and the corresponding microscopic studies have provided mechanistic insight into the cage formation. Furthermore, a non-covalent post-synthetic strategy has been adopted to functionalize the micronic cubes or cages with chromophores rendering the resulting hybrids green fluorescent.

Molecular recognition driven self-assembly and chiral induction in naphthalene diimide amphiphiles.

Naphthalene diimide amphiphiles functionalized with the dipicolylethylenediamine motif self-assemble with tunable chirality upon molecular recognition with various adenosine phosphates and competitive guest binding leads to the dynamic helix reversal of these assemblies.