title: Thermally induced single crystal to single crystal transformation leading to polymorphism.
abstract: The robust complex [La(1,10-phen)2(NO3)3] (1,10-phen=1,10-phenanthroline) exhibits thermally induced single crystal to single crystal transformation from one polymorphic phase to another. The complex crystallizes in monoclinic C2/c space group with C2 molecular symmetry at 293K while at 100K it shows P21/c space group with C1 molecular symmetry. Supramolecular investigation shows that at 100K the complex forms 2D achiral sheets whereas at 293K forms two different homochiral 2D sheets. Low temperature DSC analysis indicates that this structural transformation occurs at 246K and also this transformation is reversible in nature. We have shown that thermally induced coherent movement of ligands changes the molecular symmetry of the complex and leads to polymorphism. Photoluminescence property of complex has been studied in both solid state and in methanolic solution at room temperature. The effect of the presence low-lying LUMO orbital of π-character in the complex is elucidated by theoretical calculation using DFT method.
authors.affiliation: Department of Physics, Jadavpur University, Kolkata 700032, India.
authors.forename: Rajat
authors.initials: R
authors.lastname: Saha
authors.affiliation: Department of Physics, Jadavpur University, Kolkata 700032, India.
authors.forename: Susobhan
authors.initials: S
authors.lastname: Biswas
authors.affiliation: Department of Physics, Jadavpur University, Kolkata 700032, India; Department of Physics, NITMAS, 24-paragana(S) 743368, India.
authors.forename: Sanjoy Kumar
authors.initials: SK
authors.lastname: Dey
authors.affiliation: Department of Physics, Jadavpur University, Kolkata 700032, India.
authors.forename: Arijit
authors.initials: A
authors.lastname: Sen
authors.affiliation: Applied Material Science Division, SINP, Kolkata 700064, India.
authors.forename: Madhusudan
authors.initials: M
authors.lastname: Roy
authors.affiliation: Department of the Geophysical Sciences, The University of Chicago, USA.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Steele
authors.affiliation: Department of Chemistry, University of Kalyani, Kalyani, Nadia, India. Electronic address: kdey_chem.@rediffmail.com.
authors.forename: Kamalendu
authors.initials: K
authors.lastname: Dey
authors.affiliation: Department of Chemistry, University of Calcutta, Kolkata 700009, India. Electronic address: ghosh_59@yahoo.com.
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Ghosh
authors.affiliation: Department of Physics, Jadavpur University, Kolkata 700032, India. Electronic address: kumars@phys.jdvu.ac.in.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Kumar
mesh_terms: D002152:Calorimetry, Differential Scanning; D003460:Crystallization; D018360:Crystallography, X-Ray; D005453:Fluorescence; D006358:Hot Temperature; D006860:Hydrogen Bonding; D021621:Imaging, Three-Dimensional; D008024:Ligands; D049449:Luminescence; D008968:Molecular Conformation; D009566:Nitrates / Q000737:chemistry; D016011:Normal Distribution; D044367:Phase Transition; D010618:Phenanthrolines / Q000737:chemistry*; D010777:Photochemistry
chemical_list: D008024:Ligands; D009566:Nitrates; D010618:Phenanthrolines; C025205:1,10-phenanthroline
keywords: Homochirality and achirality; Photoluminescence; Polymorphism; Single crystal to single crystal transformation; Supramolecular interactions