Synthesis and characterization of mono- and bis-D-π-A cryptand derivatives for second-order nonlinear optics and its modulation with different metal ion inputs

Two new classes of mono- and bis-D-π-A cryptand derivatives with a flexible and a rigid cryptand core have been synthesized. The linear and nonlinear optical properties of these molecules are probed. The three dimensional cavity of the cryptand moiety has been utilized to modulate the SHG intensity to different extents in solution with metal ion inputs such as NiII, CuII, ZnII, and CdII. We also report that decomplexation events can be used to reversibly modulate their NLO responses

Deconvolution of a multi-component interaction network using systems chemistry

Abstract We describe the stepwise construction of an 8-component self-sorted system (1 - 8) by the sequential addition of components. This process occurs via a large number of states (28 = 256) and even a larger number of pathways (8! = 40320). A pathway (5, 6, 7, 8, 4, 3, 2, then 1) that is self-sorted at every step along the way has been demonstrated experimentally. Another pathway (1, 8, 3, 5, 4, 7, 2, then 6) resembles a game of musical chairs and exhibits interesting shuttling of guest molecules among hosts. The majority of pathways - unlike the special ones described above - proceed through several non self-sorted states. We characterized the remainder of the 40320 pathways by simulation using Gepasi and describe the influence of concentration and binding constants on the fidelity of the self-sorting pathways

A new class of three dimensional D-π-A trigonal cryptand derivatives for second-order nonlinear optics

Synthesis, crystal structures, linear and nonlinear optical properties of tris D-π-A cryptand derivatives with C3 symmetry are reported. Three fold symmetry inherent in the cryptand molecules has been utilized for designing these molecules. Molecular nonlinearities have been measured by hyper-Rayleigh scattering (HRS) experiments. Among the compounds studied, L1 adopts non-centrosymmetric crystal structure. Compounds L1, L2, L3 and L4 show a measurable SHG powder signal. These molecules are more isotropic and have significantly higher melting points than the classical p-nitroaniline based dipolar NLO compounds, making them useful for further device applications. Besides, different acceptor groups can be attached to the cryptand molecules to modulate their NLO properties

The first D-π-A octupolar cryptand molecule to exhibit bulk non-linearity

The cryptand derivative has H-bond mediated trigonal network structure that leads to octupolar bulk nonlinearity

Urea-based constructs readily amplify and attenuate nonlinear optical activity in response to H-bonding and anion recognition

Urea-based molecular constructs are shown for the first time to be nonlinear optically (NLO) active in solution. We demonstrate self-assembly triggered large amplification and specific anion recognition driven attenuation of the NLO activity. This orthogonal modulation along with an excellent nonlinearity-transparency trade-off makes them attractive NLO probes for studies related to weak self-assembly and anion transportation by second harmonic microscopy

Laterally non-symmetric aza-cryptands: synthesis, catalysis and derivatization to new receptors

Cryptands where the two bridgehead atoms like N or C or benzene units are connected by three bridges such that the donor atoms about the bridgeheads are different can be called laterally non-symmetric cryptands. These cryptands constitute a class which can be useful in several contemporary areas of research. The present article describes the synthesis of the cryptands and the use of metal cryptates in homogeneous catalysis, in the photochemical splitting of water to generate H<SUB>2</SUB>, in the cleavage of nucleic acids as chemical nucleases. These cryptands can be derivatized to have new receptors which might be useful as well

Binding of nitrate anion in a supramolecularly constructed macrocycle

2316-2319A laterally nonsymmetric cryptand incorporating three secondary amino nitrogens in the three bridges, have been selectively mono-derivatized with 2,4-dinitrobenzene. The product upon acidification with nitric acid, forms a macrocyclic cavity thro ugh hydrogen bonding interactions. This macrocyclic cavity accepts two nitrate an ions which has been characterized by X-ray crystallography

Recent Advances in Organic Radicals and Their Magnetism

The review presents an overview of the organic radicals that have been designed and synthesized recently, and their magnetic properties are discussed. The π-conjugated organic radicals such as phenalenyl systems, functionalized nitronylnitroxides, benzotriazinyl, bisthiazolyl, aminyl-based radicals and polyradicals, and Tetrathiafulvalene (TTF)-based H-bonded radicals have been considered. The examples show that weak supramolecular interactions play a major role in modulating the ferromagnetic and antiferromagnetic properties. The new emerging direction of zethrenes, organic polyradicals, and macrocyclic polyradicals with their attractive and discrete architectures has been deliberated. The magnetic studies delineate the singlet-triplet transitions and their corresponding energies in these organic radicals. We have also made an attempt to collate the major organic neutral radicals, radical ions and radical zwitterions that have emerged over the last century