Ren-Gen Xiong
E-mail xiongrg@seu.edu.cn
Fax number 86-
Mobile 86-**
NationalityChinese
Address Ordered Matter Science Research Center [OMSRC],
Southeast University [SEU], Nanjing 211189, PR China


Diplomas
Bachelor degree in Chemistry, 1982-07:
Master degree in Organic Chemistry, 1987-12:
Doctor degree in Mechanic Engineering, 1994-07:
Research Activities (Times New Roman, 11pt)
Ren-Gen Xiong who did three postdoctoral positions in Nanjing University (1994), Puerto Rico University (1996), and Brandeis University (1997), respectively, at the end of 1998, returned to Nanjing University where he stayed and became a full professor (The Cheung Kong Scholars Program in 2004). In the end of 2006 he moved to Southeast University, where he is Professor of Chemistry presently and the director of Ordered Matter Science Research Center.
Recently Representative Publications:
1. Xiong R.-G.*, et al., “Dielectric anisotropy of a homochiral trinuclear nickel(II) complex.” ; “3D framework containing Cu₄Br₄ cubane as connecting node with strong ferroelectricity.”; “Discovery of New Ferroelectrics: [H(₂)dbco](₂)·[Cl^-₃] · [CuCl₃(H₂O)(₂)] · H₂O (dbco=1,4-Diaza-bicyclo[2.2.2]octane)”; “Supramolecular Bola-Like Ferroelectric: 4-Methoxyanilinium Tetrafluoroborate-18-crown-6” J. Am. Chem. Soc., 2007, 129, 5346; 2008, 130, 10468; 2009, 131, , 42; 2009, 131, 12544; 2010, 132, 7300;2011, 133, 12780; 2012, 134, website available.“Hydrogen-Bonded Ferroelectrics Based on Metal-Organic Coordination.”; “New Ferroelectrics Based on Divalent Metal Ion Alum.” ;
2. Xiong R.-G.*, et al., “Highly stable olefiin-Cu(I) coordination oligomers and polymers .” ; “ In situ hydrothermal synthesis of tetrazole coordination polymers with interesting physical properties”; “Metal-organic complex ferroelectrics”, Chem. Soc. Rev., 2005, 34, 208; 2008, 37, (1), 84; 2011, 40, 3577.
3. Zhang W* and Xiong R.-G.*, “Ferroelectric Metal-Organic Frameworks”, Chem. Rev. 2012, 112. 1163.

Symmetry Breaking and Physical Property Anomalies near Tc
Ren-Gen Xiong, OMSRC, SEU, Nanjing, PRC
With the virtue of its symmetry selectivity optical second harmonic generation （SHG） is particularly attractive for probing the ferroelectric state. The second-order nonlinear optical polarization is given by P(2w)=c⁽²⁾E²(w) with electric fields E(w) of the incident light waves. With the second-order susceptibility c⁽²⁾º 0 for noncentrosymmetric systems only, SHG effect directly couples to the symmetry-breaking ferroelectric order parameter. Consequently, under the external stimuli conditions such as, temperature, pressure, electric field, strain and magnetic field, their dependence of c⁽²⁾ becomes more and more important to adjust whether there exists a symmetry breaking occurrence or not because most of molecule-based compounds contain many H-atoms which is less contribution to X-ray diffraction and solve their structure by theoretic addition H-atoms in Shelxl-97 program. On the other hand, most of ferroelectric phase transitions involve twin crystal. The difference between centro- and acentro-symmetry structures is isotropic by X-ray diffraction method (neutron-diffraction is exceptional). So, the physical property anomaly near phase transition point (especially temperature, Tc) is a crucial criterion to make a correct choice. In this presentation, we mainly focused on the temperature-dependent c²⁾, piezoelectric coefficient, and domains.



Figure 1 The diagrams of lateral amplitude (top left), phase (top middle) , topology (top right), vertical amplitude (bottom left) and phase (bottom middle) of TGS taken by PFM. PFM (PFM=piezoelectric force microscopy, TGS=triglycine sulphate).
References:
1. W. Zhang, R.-G. Xiong et al., Angew. Chem. Int. Ed. 2010, 49, 6608; 2011, 50, 11947.
2. W. Zhang, R.-G. Xiong, et al., Phys. Rev. Lett., 2011, 107, 147601; 2012, 108,
3. W. Zhang, R.-G. Xiong, et al., Adv. Mater. 2011, 23, 5658.
4.H.-Y. Ye, R.-G. Xiong et al., Acta Cryst. Sect. B, 2010, 66, 387.
5.H.-Y. Ye, R.-G. Xiong et al., J. Appl. Cryst. 2010, 43, 1031.
6. W. Zhang, R.-G. Xiong, et al.,Chem. Soc. Rev.2011, 40, 3577.
7W. Zhang, R.-G. Xiong, Chem. Rev. 2012, 112. 1163.