A modular design of a molecular tweezer is presented that integrates a multipolar D-𝜋-A [D: Donor, A: Acceptor] scaffold, 1-aminopyrene-based fluorophore units and L-alanine-based linkers. The synthesis of the molecule is based on two-fold aromatic nucleophilic reactions (ArS_N) and coupling reactions of the acid and amino functionalities. This molecule crystallizes in a non-centrosymmteric (P21) space group.We present its rich self-assembly characteristics that involves an array of 𝜋-stacking interactions. In addition, the molecular tweezer within its cleft forms H-bonding with two dimethylformamide molecules. Such multipolar D-𝜋-A systems containing chiral and fluorophore units are potential candidatesfor a number of electronic and photonic applications.

An efficient and a facile route to spiro-𝛽-lactams is described. 3-allyl-3-methylthio-𝛽-lactams, which are synthesized through a Lewis acid mediated C-3 alkylation of the trans-3-chloro-3-methylthio-𝛽-lactams, undergo a facile intrasulfenyl cyclization reaction in the presence of halogens like bromine and iodine to give spiro 𝛽-lactams in good yield. These halospiro-𝛽-lactams are then subjected to dehalogenation reaction using Raney-nickel. The resulting spiro-𝛽-lactams are further transformed into their sulfinyl and sulfonyl derivatives by using 𝑚-chloroperbenzoic acid as an oxidant.

The present work demonstrates the single crystal X-ray and DFT analysis of $ [{(2,4-CH_{3})_{2}C_{6}H_{3}O}_{2}$PS_{2}HNEt_{3}]$ (1) and $ [{(3,4-CH_{3})_{2}$ $C_{6}H_{3}O}_{2}$ $PS_{2}HNEt_{3}]$ (2) along with computational analysis of $ [{(3,5-CH_{3})_{2}C_{6}H_{3}O}_{2} $PS_{2}HNEt_{3}]$ (3) by using density functional theory (DFT) in its hybrid form B3LYP method. Compounds1 and 2 crystallize in the orthorhombic space group Pbca and triclinic space groupP1,respectively andtheir X-ray analysis reveals that phosphorus atom is coordinated to the two S and two O atoms to form tetrahedralgeometry. The structure is stabilized by cation–anion N–H.... S hydrogen bonded interactions. The structuralparameters, vibrational bands and energy gaps of frontier orbitals (HOMO–LUMO) have been calculated.The calculated geometric and spectral results matched the experimental data with good agreement. Theoreticallycalculated frontier molecular orbitals (HOMO–LUMO) and their energies suggest that charge transferoccurs within the compounds.

Thiophene-2-carbaldehyde / acetaldehyde-N¹-substituted thiosemicarbazones {R¹R²C² = N³ - N(H)- C¹(=S)N¹HR; R¹, R², R : C₄H₃S, H, Me, Httsc- NMe; C₄H₃S, H, Et, Httsc-NEt; C₄H₃S, H, Ph, Httsc-NPh; C₄H₃S, Me, Et, Hattsc-NEt} and furan-2-carbaldehyde-N-ethyl thiosemicarbazone (C₄H₃O, H, Et, Hftsc-NEt) were reacted with silver(I) halides/silver(I) acetate in presence of triphenylphosphine in organic solvents. These reactions yielded a series of dinuclear [Ag₂(μ-Br)₂ (κ-S-Httsc-NEt)2(PPh3)2]·2MeOH 1, [Ag2Cl2(κ1-SHttsc-NPh)2(μ-S,S-Httsc-NPh)2] 2, [Ag2Cl2(μ-S-Hftsc-NEt)2(κ1-S-Hftsc-NEt)2] 4, [Ag2(μ3-N3,S-ttsc-NMe)2 (Ph3P)2]·2(CH3)2CO 5, [Ag2 (μ3-N3,S-attsc-NEt)2(Ph3P)2]·0.5(CH3)2CO 6 and mononuclear [AgBr(κ1-SHttsc-NPh)(PPh3)2]· MeCN 3 complexes, all of which have been characterized using analytical techniques, IRand NMR spectroscopy, and X-ray crystallography. Thio-ligands bind in neutral form in complexes 1-4 and in anionic form in complexes 5-6. Further, the sulfur donor atoms have shown variable coordination modes incomplexes, namely, κ1-S in 1 and 3; κ1-S, μ-S in 4; κ1-S, μ-S,S (thiopheneyl-thione) in 2 and μ3- N3, S in 5 and 6. Tertiary-phosphine (PPh3) showed dual function of ligation/de-ligation towards silver(I) chloride during the synthesis of complexes 2 and 4. The bridge bonding of Httsc-NPh in 2 through thiopheneyl ring sulfur andthione sulfur is unprecedented in metal-thiosemicarbazone chemistry.

Reaction of [PdCl ₂ (PPh ₃) ₂] with imidazolidine-2-thione {SC₃H₄ (NH) ₂} in the presence of triethylamineinvolved activation of N–H bonds and formed an unusual oxo-bridged dianion, (SC ₃H ₄N ₄–O–N ₂C ₃H ₄S) ² ⁻ coordinated to Pd^II in [Pd{κ ³–S, O,S–(SC ₃H ₄N ₂–O–N ₂C ₃H ₄S)}(PPh₃)]•CH₃CN 1, which hasbeen studied using elemental analysis, IR, NMR, X-ray crystallography and ESI-mass studies.