Programmed molecular assemblies with molecular-level precision have always intrigued mankind in the quest to master the art of molecular engineering. In this regard, our review seeks to highlight the state of the art in supramolecular engineering. Herein we describe two-dimensional (2D) nanoarchitectonics of organic and organic-inorganic based hybrid materials. Molecular systems ranging from simpler hydrogen bonding driven bis-acylurea and cyclic dipeptide derivatives to complex peptoids, arylenes, cucurbiturils, biphenyls, organosilicons and organometallics, which involve a delicate interplay of multiple noncovalent interactions are discussed. These specifically chosen examples illustrate the molecular design principles and synthetic protocols to realize 2D nanosheets. The description also emphasizes the wide variety of functional properties and technological implications of these 2D nanomaterials besides an outlook for future progress.

Molecular‐interaction‐induced organizations are the basis of various biological and nonbiological systems. The molecular recognition process involved in the formation of such systems is rather complicated, as it constitutes a subtle balance of various noncovalent interactions. The molecular organization of electron‐deficient aromatic systems is particularly appealing, as they are the potential candidates for a variety of applications. The main challenge in organizing aromatic moieties lies in controlling and optimizing the relatively strong π–π interactions by appropriate functionalization. Herein, we describe a simple molecular design involving phenylalanine methylester‐functionalized naphthalenediimide (L‐NDI and D‐NDI) to achieve high‐level molecular ordering by solution processing. NDIs are among the most promising organic n‐type semiconductors. However the molecular ordering of these organic entities determines their optimal functioning in an organic device. Highly crystalline free‐floating nanosheets with large lateral dimensions were obtained for the first time through molecularly engineered self‐assembly of L‐NDI and D‐NDI systems. Interestingly the nanosheets exhibit a remarkable conductivity of 1.6 S cm−1. Furthermore the molecular organization of L‐NDI was tuned into container‐like complex architectures by employing chlorinated‐ co‐solvent‐mediated halogen bonding. The composition and the type of chlorinated co‐solvent resulted in the formation of nanocups, mesocups, and bowl‐like architectures. The nanocups possess a net volume of 0.1–1.5 attoliters (10−18 L) and can be used as containers for miniaturized applications.

The term architectonics has its roots in the architectural and philosophical (as early as 1600s) literature that refers to "the theory of structure" and "the structure of theory", respectively. The concept of architectonics has been adapted to advance the field of molecular self-assembly and termed as molecular architectonics. In essence, the methodology of organizing molecular units in the required and controlled configurations to develop advanced functional systems for materials and biological applications comprises the field of molecular architectonics. This concept of designing noncovalent systems enables to focus on different functional aspects of designer molecules for biological and nonbiological applications and also strengthens our efforts toward the mastery over the art of controlled molecular self-assemblies. Programming complex molecular interactions and assemblies for specific functions has been one of the most challenging tasks in the modern era. Meticulously ordered molecular assemblies can impart remarkable developments in several areas spanning energy, health, and environment. For example, the well-defined nano-, micro-, and macroarchitectures of functional molecules with specific molecular ordering possess potential applications in flexible electronics, photovoltaics, photonic crystals, microreactors, sensors, drug delivery, biomedicine, and superhydrophobic coatings, among others. The functional molecular architectures having unparalleled properties are widely evident in various designs of Nature. By drawing inspirations from Nature, intended molecular architectures can be designed and developed to harvest various functions, as there is an inexhaustible resource and scope. In this Account, we present exquisite designer molecules developed by our group and others with an objective to master the art of molecular recognition and self-assembly for functional applications. We demonstrate the tailor-ability of molecular self-assemblies by employing biomolecules like amino acids and nucleobases as auxiliaries. Naphthalenediimide (NDI), perylenediimide (PDI), and few other molecular systems serve as functional modules. The effects of stereochemistry and minute structural modifications in the molecular designs on the supramolecular interactions, and construction of self-assembled zero-dimensional (OD), one-dimensional (1D), and two-dimensional (2D) nano- and microarchitectures like particles, spheres, cups, bowls, fibers, belts, helical belts, supercoiled helices, sheets, fractals, and honeycomb-like arrays are discussed in extensive detail. Additionally, we present molecular systems that showcase the elegant designs of coassembly, templated assembly, hierarchical assembly, transient self-assembly, chiral denaturation, retentive helical memory, self-replication, supramolecular regulation, supramolecular speciation, supernon linearity, dynamic pathway complexity, supramolecular heterojunction, living supramolecular polymerization, and molecular machines. Finally, we describe the molecular engineering pri...

Nature's elegant molecular designs and their assemblies with specific structure-property correlations have inspired researchers to design and develop bio-mimics for advanced functional applications. To realize such advanced molecular materials, naturally evolved amino acids are arguably the ideal auxiliaries due to their remarkable molecular/chiral recognition and distinctive sequence specific self-assembling properties. Over the years, this modular approach of derivatizing naphthalenediimides (NDIs) and perylenediimides (PDIs) with amino acids and peptides have resulted in several hitherto unknown molecular assemblies with phenomenal impact on their performance. Derivatization with versatile arylenediimides is especially interesting due to their wide spread applications in fields ranging from biomedicine to electronics. Herein some of these seminal reports of this rapidly emerging field and the design principles embraced are discussed.

Right or left paradox: Homochiral, heterochiral and achiral peptide auxiliaries appended with naphthalenediimide (NDI, see figure) were employed to demonstrate chiral transcription. We report an interesting phenomenon coined as retentive helical memory. Remarkably, NDI-peptide conjugates were tuned into hierarchical 1D molecular assemblies of opposite helicity in case of homochiral peptide auxiliaries.