MECHANISMS FOR MOLECULAR COMPLEX FORMATION AND FACTORS WHICH DOMINATE MOLECULAR ORIENTATION IN MOLECULAR COMPLEXES

^将D_2O中四[4- （n -甲基）吡啶]卟啉（TMPyP）的1H NMR谱与周围含有3个吡啶和1个苯基（TriMPyP）和2个吡啶和2个苯基（DiMPyP）的卟啉进行了比较。光谱结果表明，尽管卟啉正电荷之间存在静电斥力，但TriMPyP和DiMPyP都是通过范德华相互作用形成二聚体的。由此可见，水中卟啉环之间的相互作用非常强，形成二聚体的吸引力超过了静电斥力。另一方面，即使在高浓度和/或无机盐存在的情况下，TMPyP也以单体形式存在于水中。在这种情况下，静电斥力克服了范德华引力。以四芳基卟啉为探针，研究了离子客体分子在疏水环糊精（CDx）空腔中的包合机理。在卟啉的邻位具有阴离子或非离子取代基的苯基被天然-环糊精（- cdx）松散地包含，而阳离子邻位几乎不包括在- cdx空腔中。阴离子和非离子卟啉与七甲基（三o -甲基）- β - cdx （tme - β - cdx）形成非常稳定的包合物。同时，阳离子卟啉完全不与tme - β - cdx形成络合物。这些现象可以用微观极化的CDx腔来解释，阴离子客体更适合停留，而阳离子客体由于宿主和客体之间的静电排斥而形成非常不稳定的复合物。已知CDx是识别中心手性的不良宿主。事实上，天然cdx和烷基化cdx对氨基酸及其衍生物的手性识别能力非常弱。然后我们尝试用质子化胺化CDxs来进行库仑相互作用。质子化氨基- β - cdxs可以区分n -乙酰基氨基酸和扁桃酸及其相关酸的(R)和(S) -对映体。宿主和客体之间的库仑相互作用以及客体进入CDx腔需要实现手性识别。少

^1H NMR spectra of tetrakis [4- (N-methyl) pyridinium] porphyrin (TMPyP) in D_2O was compared with those of prophyrins having three pyridinium groups and one phenyl group (TriMPyP) and two pyridinium groups and two phenyl groups (DiMPyP) at the peri positions. The spectra indicate that both TriMPyP and DiMPyP form their dimers through van deb Waals interaction in spite of the electrostatic repulsion between the positive charges of the porphyrins. It might be concluded that the pi-piinteraction between the porphyrin rings in wateris so strong that the attractive force to form the dimers overcomes the electrostatic repulsive force. On the other hand, TMPyP exists as the monomer form in water even at high concentrations and/or in the presence of inorganic salt. In such a case, the electrostatic repulsive force overcomes the van der Waals attractive force.Tetraarylporphyrins were used as probes to study the mechanism for inclusion of ionic guest molecules into the hydrophobic cyclodextrin … More (CDx) cavities. The phenyl groups having anionic or nonionic substituents at the peripositions of the porphyrins are loosely included by native-beta-cyclodextrin (beta-CDx) while the cationic peripheries are hardly included into the beta-CDx cavity. Anionic and nonionic porphyrins form very stable inclusion complexes with heptakis (tri-O-methyl) -beta-CDx (TMe-beta-CDx). Meanwhile, cationic porphyrins do not form the complexes with TMe-beta-CDx at all. These phenomena can be intepreted in terms of the microscopically polarized CDx cavity where anionic guest is preferable to stay but cationic guest forms very unstable complex because of electrostatic repulsion between the host and the guest.It has been known that CDx are poor hosts to recognize central chirality. Indeed, native and alkylated CDxs have very weak ability to recognize the chirality of amino acids and their derivatives. Then we tried to use coulomb interaction by using protonated aminated CDxs. Protonated amino-beta-CDxs can discriminate between the (R) -and (S) -enantiomers of N-acetyl amino acids and mandelic acid and its related acids in their dissociated forms. The coulomb interaction between the host and the guest as well as inclusion of the guest into the CDx cavity needs to achieve the chiral recognition. Less