X-Ray Crystallography and Crystal Engineering

Accurate data on molecular structure is of major importance in several scientific fields: chemistry, physics, materials science and biology.

X-ray diffration is one of the best tools for structural analysis. All is needed to unravel the molecular structure is a very small crystal or, in favourable cases, a polycrystalline sample. Careful measurements of the diffraction pattern of X-rays scattered by the crystalline sample can be used to accurately determine the molecular geometry (bond lengths and valency angles) and may also give invaluable information about the electron densitiy distribution and chemical bonding.

The CEMDRX is equipped with several single-crystal and powder diffractometers, including one state of the art 4-circle diffractometer equipped with a 4k CCD detector (see list of equipment).  Measurements from room temperature down to ~ 30K are possible on single-crystal and polycristalline materials from 475 K down to ~28 K.

Current research topics

• atropisomerism in diphenylguanidine (DPG) salts and derivatives
• low-dimensional magnetism in cooper(II) salts
• ferroelectric compounds based on betaine and derivatives
• molecular rotors (anilinium salts)
  
• 3d and 4d metal complexes of N-alkylated aminoacids
• fluorine chelation of lanthanides and transition metal atoms as NMR relaxation agents
• new materials for non-linear optics based on hyperpolarizable molecules
• supramolecular componds (porphyrins and precursors)
• weak intramolecular interactions (C-H...pi hydrogen bonds)
• chiral compounds used in enantioselective asymmetric synthesis
• steroids with potencial pharmacological activity againts breast cancer.

Collaborations

There are strong on-going collaborations with several external research groups in Physics, Chemistry, Biochemistry, Pharmacy and Materials Science:

• Dept. de Ingeniería Agrícola y Forestal, Universidad de Valladolid, Spain
• Laboratório de Química Farmacêutica, Univ. Coimbra
• Centro de Química, Dept. of Chemistry, FCTUC
• Dept. of Chem. Engineering, FCTUC
• Dept. of Physics, University of Porto
• Dept. of Physics, University of Minho
• Dept. of Chemistry, University of Minho
  
• Escola Superior Agrária, IPCB, Castelo Branco
• REQUIEMTE, Univ. Porto
  
• Chymiotechnon, Univ. Coimbra
• Institut for History of Art, FLUC
• National Museum Machado de Castro, Coimbra
• Museu de Lamego