Rational synthesis of heteroleptic lanthanide sandwich...

Details Rational synthesis of heteroleptic lanthanide sandwich... Rational synthesis of heteroleptic lanthanide sandwich...

2002-04-29

2003-11-04

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C540S145000, C534S015000, C556S001000, C365S106000, C365S151000, C365S153000, C365S173000

Reexamination Certificate

active

06642376

ABSTRACT:

FIELD OF THE INVENTION
The present invention concerns methods of making triple decker sandwich coordination compounds and intermediates useful for carrying out such methods.
BACKGROUND OF THE INVENTION
The storage of information at the molecular level can afford extraordinarily high memory densities. An approach toward molecular-based information storage that involves the storage of data in distinct molecular oxidation states has been developed. (see, e.g., Lindsey, U.S. Pat. No. 6,212,093; Roth, et al. (2000)
J. Vac. Sci. Technol. B
18:2359-2364; Gryko, et al. (2000)
J. Org Chem.
65:7345-7355; Gryko, et al. (2000)
J. Org. Chem.
65:7356-7362; Clausen, et al. (2000)
J. Org. Chem.
65:7363-7370; Clausen, et al. (2000)
J. Org Chem.
65:7371-7378; Li, et al. (2000)
J. Org. Chem.
65:7379-7390; Gryko, et al. (2001)
J. Mater. Chem.
11: 1162-1180). Thiol-derivatized redox-active molecules are attached to an electroactive surface, thereby enabling reading and writing to be achieved via electrical methods (Roth, et al.
Anal. Chem.
submitted). The information storage density can be increased commensurate with the number of available oxidation states of the molecules in a memory storage location.
Among the various classes of molecules examined for information storage, (Gryko, et al. (2000)
J. Org. Chem.
65:7345-7355; Gryko, et al. (2000)
J. Org. Chem.
65:7356-7362; Clausen, et al. (2000)
J. Org. Chem.
65:7363-7370; Clausen, et al. (2000)
J. Org. Chem.
65:7371-7378) the triple-decker lanthanide sandwich molecules (Tran-Thi, T. -H. (1997)
Coord. Chem. Rev.
160:53-91; Ng and Jiang (1997)
Chem. Soc. Rev.
26:433-442) comprised of porphyrinic ligands proved most attractive due to their large number of redox states, reversible electrochemistry, and relatively low oxidation potentials. The triple deckers generally exhibit four oxidation states in the range 0-1.4 V (vs Ag/Ag
+
), corresponding to the formation of the monocation, dication, trication, and tetracation (Li, et al. (2000)
J. Org. Chem.
65:7379-7390; Gryko, et al. (2001)
J. Mater. Chem.
11: 1162-1180). A further attraction of this class of molecules stems from the possibility of interleaving the potentials of two triple deckers, thereby achieving as many as eight accessible cationic oxidation states. This approach for molecular-information storage requires the ability to synthesize triple deckers of a given type bearing linkers for attachment to an electroactive surface.
The synthesis of homoleptic porphyrin triple deckers, first reported by the groups of Buchler (Buchler and Knoff (1985) In:
Optical Properties and Structure of Tetrapyrroles;
Blauer, G.; Sund, H., Eds.; de Gruyter: Berlin, pp 91-105) and Weiss (Buchler, et al. (1986)
J. Am. Chem. Soc.
108:3652-3659), employed the reaction of a lanthanide acetylacetonate complex with a porphyrin in refluxing 1,2,4-trichlorobenzene (1,2,4-trichlorobenzene has bp 214° C.; the oil bath temperature for these reactions was set at ~230° C.). This procedure grew out of a method developed by Horrocks for the preparation of (Por)M(acac) complexes by reaction of a porphyrin with a lanthanide(acac) complex in refluxing 1,2,4-trichlorobenzene (Wong, et al. (1974)
J. Am. Chem. Soc.
96:7149-7150; Wong, C. -P. (1983)
Inorg. Synth.
22:156-162). The synthesis of heteroleptic (porphyrin/phthalocyanine) triple deckers has been achieved by two distinct procedures, an undirected “reaction-of-monomers” route and a directed “monomer+dimer” route (vide infra). The former route proceeds as follows: A porphyrin is treated with excess M(acac)
3
.nH
2
O in refluxing 1,2,4-trichlorobenzene, affording the porphyrin.M(acac) complex (Moussavi, et al. (1986)
Inorg. Chem.
25:2107-2108). The mixture is then treated with a dilithium phthalocyanine under continued reflux. In various applications of this method it has become clear that the product composition depends on the lanthanide, the nature of the substituents on the porphyrin and phthalocyanine, and the ratio of the reactants (Ng and Jiang (1997)
Chem. Soc. Rev.
26:433-442). In our hands, the reaction-of-monomers route using M═Eu afforded two double deckers of composition (Por)M(Pc) and (Pc)M(Pc), and three triple decker complexes of composition (Por)M(Pc)M(Por), (Pc)M(Por)M(Pc), and (Pc)M(Pc)M(Por); the yields of the three types of triple deckers were typically 10-20%, <3%, and 10-14%, respectively, upon chromatographic purification (Li, et al. (2000)
J. Org. Chem.
65:7379-7390).
Accordingly, there remains a need for new methods for the rational synthesis of heteroleptic lanthanide sandwich coordination complexes.
SUMMARY OF THE INVENTION
A first aspect of the present invention is a half-sandwich coordination complex, useful for the synthesis of triple-decker sandwich coordination compounds, produced by the process of: reacting a precursor complex of the formula XM(R
1
)
2
with a free base porphyrinic macrocycle to produce said half-sandwich complex, wherein X is a halogen, M is a metal (e.g., a metal selected from the group consisting of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), and R
1
is an amide.
The precursor complex may be produced by reacting a compound of the formula MX
3
, wherein M is a lanthanide metal and X is halogen, with a compound of the formula ZR
1
, wherein Z is a counter-ion and R
1
is an amide, to produce the precursor complex of the formula X-M(R
1
)
2
.
Alternatively stated, the present invention provides a half-sandwich coordination complex, useful for the synthesis of triple-decker sandwich coordination compounds, according to Formula (I):
L-M-X  (I)
wherein X is a halogen; M is a metal (e.g., a metal selected from the group consisting of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), and L is a porphyrinic macrocycle group.
A further aspect of the present invention is a method of making a half sandwich coordination complex, comprising the steps of: reacting a precursor complex of the formula X-M(R
1
)
2
, with a free base porphyrinic macrocycle to produce said half-sandwich complex; wherein X is a halogen, M is a metal (e.g., a metal selected from the group consisting of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), and R
1
is an amide.
A further aspect of the present invention is a method of making a triple-decker sandwich coordination compound, comprising the step of reacting a half-sandwich coordination complex as described above with a double-decker sandwich coordination compound, preferably in a polar aprotic solvent, and preferably at a temperature of at least 100° C., to produce said triple-decker sandwich coordination compound.
The foregoing and other objects and aspects of the present invention are explained in greater detail below.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The terms “sandwich coordination compound” or “sandwich coordination complex” refer to a compound of the formula L
n
M
n−1
, where each L is a heterocyclic ligand (as described below), each M is a metal, n is 2 or more, most preferably 2 or 3, and each metal is positioned between a pair of ligands and bonded to one or more hetero atom (and typically a plurality of hetero atoms, e.g., 2, 3, 4, 5) in each ligand. Thus sandwich coordination compounds are not organometallic compounds such as ferrocene, in which the metal is bonded to carbon atoms. The ligands in the sandwich coordination compound are generally arranged in a stacked orientation (i.e., are generally cofacially oriented and axially aligned with one another, although they may or may not be rotated about that axis with respect to one another). See, e.g., D. Ng and J. Jiang, Sandwich-type heteroleptic phthalocyaninato and porphyrinato metal complexes,
Chem. Soc. Rev.
26, 433-442 (1997).
The term “double-decker sandwich coordination compound” refers to a sandwich coordination compound as described above where n is 2, thus having the formula L
1
-M
1
-L
2
, wherein each of L
1
and L
2
may be the same or different. See, e.g., J. Jiang et al., Double-decker Yttrium(III) Complexes wit

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