Building Large Structures with Curved Aromatic Surfaces by Complexing Metals with Phosphangulene

Phosphangulene (1) is
a hexacyclic triarylphosphine
with a distinctive conical shape and an electron-rich aromatic surface
that is geometrically and electronically complementary to fullerenes
such as C60 and C70. As a result, suitable derivatives
of phosphangulene can cocrystallize with fullerenes or even bind them
in solution. Surprisingly, previous work has largely overlooked the
potential of phosphangulene to form complexes with metals, which offers
a simple way to create large molecular structures with curved aromatic
surfaces. To explore this approach, we have prepared and characterized
a series of complexes of phosphangulene with Ag+ and Cu+. Our results show that Phang ligands are exceptional for
many reasons. In particular, they can yield metal complexes with unique
coordination, and the metal centers hold the concave aromatic surfaces
of multiple ligands in various divergent arrays. Moreover, the rigid
conical structure of phosphangulene gives the complexes an awkward
shape that cannot be packed efficiently without complementary partners.
As a result, metal complexes of phosphangulene are predisposed to
cocrystallize with fullerenes, thereby yielding materials in which
metals and fullerenes are brought together in ordered arrangements.

磷环烯(Phosphangulene (1))是一种六环三芳基膦，具有独特的圆锥结构与富电子芳香表面，在几何与电子层面均可与C60、C70等富勒烯形成互补。因此，合适的磷环烯衍生物可与富勒烯共结晶，甚至在溶液中与之结合。令人意外的是，此前的研究大多忽略了磷环烯与金属形成配合物的潜力——这一途径可便捷构建带有弯曲芳香表面的大型分子结构。为探究这一研究方向，我们制备并表征了一系列磷环烯与Ag+、Cu+形成的配合物。我们的研究结果表明，Phang配体（磷环烯配体）具备诸多优异特性。具体而言，此类配体可形成具有独特配位模式的金属配合物，金属中心可将多个配体的凹面芳香表面以多种发散式排布进行固定。此外，磷环烯的刚性圆锥结构使得配合物呈现出特殊的空间构型，若无互补性客体则无法实现高效堆积。因此，磷环烯的金属配合物倾向于与富勒烯共结晶，最终得到金属与富勒烯按有序方式排布的功能材料。