| 摘要: | 此研究計劃係一二年期“含金屬中心雜環結構之中間相材料”計畫之延伸。於此計劃中我們將繼續運用含單/多重無機金屬中心結構，來設計與製備具有中間液晶相之錯合物。計劃中將設計多系列具五或六圓環結構之雜環衍生物，具五圓及六圓環之雜環結構擁有多項特色，適合與多數過渡金屬配位產生結構特殊之配位化合物。這些特色有；例如：(1)其化學性質或結構穩定性；(2)中心結構較不具共平面性，其對稱性較低；(3)多數具PL光學性質，可開發成發光材料；(4)配位方式多樣性。計劃將探討其可能產生中間相材料之性質，除具中間液晶相之探討與全鑑定外，也將探討其磁性、導電性及/或發光性等之超結構性質。此類材料之分子結構基本上是具有剛硬中心四面角錐體或平面四邊形結構之分子組合體。錯合物結構具四面角錐體以VO2+或TiO2+等金屬中心為主，而平面四邊形結構以Cu2+, Pd2+, Ni2+, Mn2+等金屬中心為主；偶有四面體則以Co2+, Zn2+等金屬中心為主。一般而言，四面角錐體及平面四邊形結構較易形成中間相，而四面體因不易堆疊，較不易形成中間相。金屬中心核數有單核(mononuclear)、雙核(binuclear)及多核(polynuclear)。金屬配位數(coordination number, CN)則以CN= 4 (Cu2+/Ni2+/Pd2+/Zn2+, CH =5 (VO2+/TiO2+或CN = 6為主(Al3+/Fe3+/Ru3+/Cr3+)。偶有CN = 3；例如：Ag1+/Cu1+。於系統中我們將利用液晶分子極性自身排列組合，無機金屬分子形狀之特殊設計及吸引力，以誘導超分子規則排列之特性，來設計此類具中間相材料。上述方式也將被廣泛運用來加速此類中間相材料之形成。此外，也將利用調整分子常與寬之比例不同，來進行誘導據不同中間相材料之產生。且利用調整分子與分子間之微弱作用力，來形成液晶材料。某些具金屬氧(M=O)及金屬鹵(M-X)結構之中心離子，於計畫中將被嵌入有機系統中，來形成單分子之微小磁偶距。此微小磁偶距及分子具非對稱性中心，將是此類材料具有整體極性之必要先決條件，此整體極性也更為其他多種此類材料物性之起源基點。此外，也將藉外加磁場導致分子磁性之重新排列，且能使順磁分子(paramagnetic)結構之順磁性現象持續維持，來產生磁性材料。無機與有機中間相基分子結構之最大區分，在於分子進入中間相狀態中分子與分子之間，相互吸引作用力之難易度及強弱大小。有效利用液晶分子自身排列組合之特性，金屬特殊配位之幾何形狀，以及極弱之分子分子間鍵結力，將會於此研究計劃中，被廣泛運用來加易此種具中間相材料之設計與合成。重點將繼續集中於此類材料之設計與合成，以及未來研究方向將朝向於材料光電行性質之探討。 This proposal continues our original research in metallomesogen derived from heterocycles. This research is to propose a strategic approach for the formation of novel metallomesogenic materials with superstructures, which are expected to exhibit liquid crystalline behavior, magnetic and related electro-optical properties. These materials are associated with unique molecular assemblies in which metal centers as core group have geometries of square planar or pyramid with a coordination number of 4, 5 and 6. Four different types of heterocyclic structures are applied to generate the metallomesogenic materials; (a) pyrazoles (b) benzoxazoles (c), 1,2,4-triazzoles, and (d) 1,3,4-oxadiazes. A variety of transition metals will be incorporated to induce the microscopic dipole, and the choice of the metals incorporated will be generally dependent on the coordination geometry, oxidation state or electronic state of the metals. Metal complexes incorporated with a twisted square planar (Cu2+), square planar structure (Ni2+/Pd2+) are often easier to form mesophases, however, complexes with a tetrahedron (Co2+/Zn2+) is not easy to form a mesophase due to unfavorable packing. A coordination number of 4 (Cu2+/Ni2+/Zn2+/Pd2+), 5 (VO2+/TiO2+/Mn2+), and 6 (Cr/3+Al/3+Ru3+/Fe3+) will be applied to generate the metal complexes. Occasionally, complexes with a CN = 3 (Cu1+/Ag1+) might be also possible. A non centrosymmetric structure and the large resulting molecular dipoles are prerequisites in order to give rise to large bulk macroscopic polarization. The ability to reorient the polarization with electric field applied and to have this polarization persist after the field is removed will make these materials polar ordering. A major distinction between metallomesogens and organic mesogens is their greater tendency to exhibit intermolecular dative coordination in the mesophase, which makes these materials attractive candidates for poling into acentric states. In these systems a lower symmetry is promoted at the molecular level by the self-ordering properties of liquid crystalline materials, the complementary shape of the molecules and head-to-tail ordering imposed by the linear chain superstructures, and these methods are also widely employed to facilitate the formation of these mesogenic materials. Self-organizing properties of liquid crystalline materials, the geometric shape of the molecules, and weak intermolecular dative coordination will be employed to facilitate the formation of the proposed materials. Preparation, characterization and mesomorphic properties of these poly-metallic compounds will be studied in the initial stage, and future research will be focused on the physical studies. 研究期間：10008 ~ 10107 |
