Rare-earth ions are characterized by their long-lived excited state, which makes them eminently suited for optical amplification, wavelength conversion ("upconversion") and sensitive diagnostics.

Complexes of rare-earth metal ions with organic molecules having macrocyclic structures are well-known in the art. Such rare-earth metal ion complexes are excited for use in the aforementioned applications. It has now been found that the efficiency of the excitation of rare-earth ions can be further enhanced by using complexes comprising at least two complexing moieties, each of which is complexed with a rare-earth metal ion. It has further been found that when such a multiple rare-earth metal complex comprises at least one, preferably organic, sensitizer, the excitation is further improved.

The idea pertains to the use of multiple complexing units, such as calixarenes, hemispherands, polyaminocarboxyiic acids or p-diketonates, in combination with rare-earth ions of one type or of various types, with or without an attached (organic) sensitizer. The combination of rare-earth ions is of interest to enhance the excitation and/or emission possibilities of such ions (e.g., by broadening the range of absorption wavelengths) and to facilitate the use of multiple photons for excitation of these ions, with the additional possibility of wavelength conversion. The use of a sensitizer forms an additional advantage. It can be used to invoke much more efficient population of the excited state: The sensitizer has an absorption

cross section which is typically 3-4 orders of magnitude higher than that of the rare-earth ion when, for instance, organic z transitions are considered.

Since the lifetime of the excited state of the organic sensitizer generally is much shorter than the lifetime of the luminescent state of the rare-earth ion, multiple ions can be brought to the excited state by the same sensitizer.

Therefore it is anticipated that a macromolecular unit consisting of several, preferably 2 or 3 complexing units, optionally, with attached rare-earth ions connected to at least one sensitizer, will serve as a very effective luminescent structure.

Both the same rare-earth ions and a combination of different rare-earth ions can be applied. Unless use is made of a particular property to influence the complexation behavior of the ligands, a statistical mixture of various combinations of rare-earth ions will be obtained when more than one rare-earth ion is used.

Preferred rare-earth metal ion complexes are complexes wherein the rare- earth metal ion is selected from Yb3+ (ytterbium(lll) ion), Y3+ (yttrium(lll) ion), Er3+ (erbium(lll) ion), Tb3+ (terbium(lll) ion), Tm3+ (thulium(lll) ion), Ho3+ (holmium(lll) ion), Eu3+ (europium(lll) ion), and Nd3+ (neodymium(lll) ion).

The macroscopic complex can be synthesized at a specific pH to tune the complexation properties of the ligands: for instance, the pK values of aromatic carboxylic acids, aliphatic carboxylic acids, and pyridine dicarboxylic acids will be different. Further, to activate ß-diketonate an alkaline treatment is required for deprotonation.

When a specific pretreatment is applied to activate a selected part of the macroscopic structure, there may be rare-earth ion exchange.

The absorption coefficients of lanthanide ions are usually low due to their weak absorption bands as compared to, e.g., organic molecules. Yb which is often used in lasers and optical amplifiers as a co-dopant, has a somewhat higher absorption coefficient than other rare-earth ions around 980 nm, where relatively inexpensive powerful lasers are available.

Therefore, it can be used for excitation and subsequent transfer of its energy to another lanthanide ion which emits light in a wavelength region that is interesting for application in optical telecommunications, e.g., Er which emits around 1530 nm. The application of this technique in current telecommunications networks renders energy transfer studies from one lanthanide ion to another important. Therefore, multiple complexes are required in which the lanthanide-lanthanide ion distance is relatively short (preferably <50 A). The energy transfer studies can be performed by detection of the luminescence of the acceptor lanthanide ion, or by a decrease of the lifetime of the luminescent excited state of the donor ion.

The latter method is most frequently used because it is easily accessible.

Another application of multiple rare-earth ion complexes which may be of interest is in frequency (or wavelength) conversion. Examples are so-called upconverting phosphori, which are well-known in inorganic crystals, but so far have no organic counterpart. Frequency upconversion can also be realized by excited state absorption processes, due to the relatively long- living excited state of rare-earth ions. For upconversion inorganic crystals containing Y3+ and Yb3+ in combination with Er3+, Ho3+, or Tm3+ have been applied. Excitation is generally done via Yb3+in the 950-1000 nm range; particularly the wavelength region around 980 nm, where relatively inexpensive powerful laser sources are available, is suitable for excitation.

Emission wavelengths depend on the composition and structure of the inorganic crystals. Emission bands in the blue (around 400 nm), green (450-500 nm), orange (530-560 nm), and red (630-690 nm) parts of the spectrum have been reported. Application of such wavelength conversion materials is expected in two areas: (1) for optical telecommunications, when one desires to convert near-lR light (as used for high transmission long distance links) to visible light (which is transmitted most efficiently by low cost, polymer based short distance networks, e.g., in the home), and (2) for sensitive diagnostics where excitation can be done in the near-lR where no interference occurs with constituents of bodily fluids or specimens and emission is effected in the visible part of the spectrum, where the most sensitive detectors presently available have their optimum sensitivity.

Suitable complexing moieties are macrocyclic structures, in particular calix[4]arenes. Calix[4]arenes are well-known building blocks in supramolecular chemistry because of their relatively easy functionalization.

They consist of four phenolic rings that are linked via methylene bridges and can adopt different conformations. The cone conformation is the most stable one. The phenolic groups are all at the same face of the molecule (lower rim) and form a cyclic array of intramolecuiar hydrogen bonds in this conformation. As a consequence of the vase-like structure of the cone conformation and the presence of four aromatic units, this building block is called the calix(4]arene ("caliX' or "chalise" is Greek for vase). The number of linked aromatic units can vary from 4 to 8, and is indicated by the number between brackets. Calix[4]arenes have been combined with several other building blocks, like resorcinarenes, cyclodextrins, terphenyls, and porphyrins, with the intention to build larger structures. This objective can also be achieved by the covalent coupling of two or more calix[4]arenes, either by lower-lower, lower-upper, or upper-upper rim linkages. By making use of functional groups containing donor atoms that are able to coordinate

to lanthanide ions, it is possible to acquire multinuclear lanthanide ion complexes.

For energy transfer between two different lanthanide ions, biscalix[4]arenes that contain two molecular cages suitable for lanthanide ion complexation can be used. The hexaester biscalix[4]arene, for instance, can be synthesized according to McKervey et al., Anew. Chem. Int. Ed. Ennl., 1990, (29), 280 and contains a sufficient number of donor atoms.

Furthermore, biscalix[4]arenes containing amide groups instead of ester functions were synthesized. The synthesis routes leading to hexaesters and hexaamides both start from p-tert-butylcalix[4]arene and consist of four reaction steps. Moreover, the combination of differently functionalized calix[4]arenes leads to non-symmetric biscalix[4]arenesthat may be capable of selective complexation of different lanthanide ions.

The invention is further illustrated by the following examples.

Examples The examples which support the present invention can be divided into three separate classes, symmetric hexaester biscalix[4]arenes (general structure 1 in Chart 1), symmetric hexaamide biscalix[4]arenes (general structure 2 in Chart 1), and asymmetric biscalix[4]arenes (general structure 3 in Chart 1).

Example 1 Synthesis of symmetric hexaester biscalix[4]arenes la-f (Scheme 1) Starting materials

Starting material p-tert-butylcalix[4]arene(4) was converted to tetraethyl ester (5) (R = terf-butyl) (according to F. Arnaud-Neu et al., J. Am. Chem. Soc.

111, (1989) 8681, and subsequently hydrolyzed to the triethyl ester monoacid derivative (6) (R = tert-butyl) (according to V. Böhmer et al., J.

Chem. Soc. Perkin Trans. 1, 1990, 431). Coupling of the calix[4]areneto a diamine spacer unit was performed via a slightly modified literature procedure. Triethyl ester monoacid chloride (7) (R = tert-butyl) was obtained from (6) in refluxing oxalyl chloride, and was reacted with 0.5 mole equivalents of the appropriate diamine in dichloromethane, in the presence of triethylamine as a base. Symmetric biscalix[4]arenes (1tBu) were purified by recrystallization, mainly from a mixture of dichloromethane and methanol (95:5; v/v), and obtained in high yields (65-76%). In all cases the main product was accompanied by tetraethyl ester (5)(R = tert-butyl). The procedure for compounds with R=H is similar to the procedure for R = tert- butyl.

General procedure for the synthesis of hexaester biscallxf4 larenes (1a-f ) Biscalix[4]arenes (la-f) were prepared according to a slightly modified literature procedure. Triester-monoacid 6 (R = tert-butyl or H) was refluxed in oxalyl chloride (5 ml) for 2 hours. After evaporation of the remaining oxalyl chloride, the monoacid chloride was dissolved in dichloromethane (30 ml) under an argon atmosphere. A solution of 0.5 mole equivalents of the corresponding diamine and triethylamine in dichloromethane (12 ml) was slowly added. The reaction mixture was stirred overnight at room temperature and subsequently quenched with an aqueous acetic acid solution (5%, 25 ml). The layers were separated, and the organic layer was washed twice with water (50 ml), followed by evaporation of the solvent. The product was recrystallized from dichloromethane/methanol (95:5; v/v) unless stated otherwise.

The following compounds were prepared: 1,3-Bis{25-[(aminocarbonyl)methoxy]5,11,17,23-tetrakis(1,1-d imethylethyl)- 26,27,28-tris[(etho-xycarbonyl)methoxy]calix[4]arene}benzene (1tBua) The reaction was performed using (6) (R = tert-butyl) (0.50 g, 0.52 mmoles), 1,3-phenylenediamine (30 mg, 0.28 mmole), and triethylamine (0.30 ml, 2.1 mmoles). A white solid was obtained in 76% yield. Mp: 132-1 340C. <BR> <BR> <BR> <BR> <BR> <P>1, 4-Bis(25-[(aminocarbonyl)methoxy]-5, 11,17, 23-tetrakis(1, 1-dimethylethyl)- 26,27,28-tris[(etho-xycarbonyl)methoxy]calix[4]arene}benzen( 1tBub) Calix[4]arene 6 (R = tert-butyl) (1.00 g, 1.04 mmoles) was coupled to 1,4- phenylenediamine (60 mg, 0.57 mmole) in the presence of triethylamine (0.60 ml, 4.2 mmoles), and (1tBub) was obtained as a white solid in 72% yield.

Mp: 258-2600C.

1,3-Bis{25-[(aminocarbonyl)methoxy]-5,11,17,23-tetrakis(1 ,1-dimethylethyl)- 26,27,28-tris[(etho-xycarbonyl)methoxy]calix[4]arene}propane (1tBud) Compound (6) (R = tert-butyl) (0.50 g, 0.52 mmole), 1,3-diaminopropane (22 1, 0.26 mmole), and triethylamine (0.30 ml, 2.1 mmoles) were used as reagents, and recrystallizationyielded (1tBud) in 76% yield. Mp: 152-1530C. <BR> <BR> <BR> <BR> <BR> <P>1, 4-Bis(25-((aminocarb on yl)meth ox y]- 5,11,17, 23-tetrakis(1, 1 -dimethylethyl)- 26,27,28-tris[(etho-xycarbonyl)methoxy]calix[4]arene}butane( 1tBue) Coupling of (6) (R = tert-butyl) (1.00 g, 1.04 mmoles) and 1,4-diaminobutane (60 pI, 0.57 mmole), in the presence of triethylamine (0.60 ml, 4.2 mmoles),

yielded (1tBue) after recrystallization from a mixture of chloroform and acetonitrile(4:1) in 65% yield. Mp: 201-2030C.

1,6-Bis{25-[(aminocarbonyl)methoxy]-5,11,17,23-tetrakis(1 ,1-dimethylethyl)- 26,27,28-tris[(etho-xycarbonyl)methoxy]calix[4]arene}hexane( 1tBuf) The double calix[4]arene (1,Buf) was obtained in 67% yield from (15) (R = tert- butyl) (1.49 g, 1.45 mmoles), 1,6-diaminohexane (84 pI, 0.73 mmole), and triethylamine (0.90 ml, 6.3 mmoles). Mp: 134-1360C.

1,3-Bis{25-[(aminocarbonyl)methoxy]-26,27,28- tris[(ethoxycarbonyl)methoxy]calix[4]arene}-benzene(1Ha) The reaction of (6) (R = H) (0.51 g, 0.69 mmole) and 1,3-phenylenediamine (40 mg, 0.37 mmole) in the presence of triethylamine (0.40 ml, 2.8 mmoles) gave white crystals in 51% yield. Mp: 137-1400C.

1, 4-Bis25-[(aminocarbonyl)methoxy]-26, 27,28- tris[(ethoxycarbonyl)methoxy]calix[4]arene}-benzene(1Hb) Compound (lob) was obtained as a white solid in 76% yield by reaction of (6) (R = H) (0.50 g, 0.67 mmole), 1,4-phenyienediamine(40 mg, 0.37 mmole), and triethylamine(0.40 ml, 2.8 mmoles). Mp: 183-1850C.

1, 2-Bis(25-[(aminocarbonyl)methoxy]-26, 27,28- tris[(ethoxycarbonyl)methoxy]calix[4]arene}-ethane(1Hc) The coupling was performed using (6) (R = H) (0.50 g, 0.67 mmole), 1,2- diaminoethane(22 (22 µl, 0.33 mmole), and triethylamine (0.40 ml, 2.8 mmoles).

Recrystallization led to (1Hc) in 59% yield. Mp: 175-177°C.

1,3-Bisf25-[(aminocarbonyl)methoxy]-26,27,28- <BR> <BR> <BR> <BR> <BR> tris[(e th oxycarb onyl) m ethoxy]calix[4]aren e)-propan e (1Hd) Reaction of (6) (R = H) (0.50 g, 0.67 mmole) with 1,3-diaminopropane (27 l, 0.32 mmole) in the presence of triethylamine (0.40 ml, 2.8 mmoles) gave (1Hd) as a white solid in 61% yield. Mp: 173-1740C.

Example 2 Synthesis of symmetric hexa-amide biscalix[4]arenes 2b,e,f (Scheme 2) General description of the synthesis The synthesis route leading to biscalix[4]arene hexaamides starts with the monoprotection of p-tert-butylcalix[4]arene (4) with 3-bromo-1-propene in N,N'-dimethylformamide using CsF as a base. The monoprotection was performed via a slightly modified literature procedure (L.C. Groenen, Conformational Prnperties of Calixarenes, PhD Thesis, University of Twente 1992). Calix[4]arene (8) was trialkylated with 2-chioro-N,N'-diethylacetamide in acetonitrile in the presence of a catalytic amount of potassium iodide and potassium carbonate as a base. After work up and recrystallization from acetonitrile, compound (9) was obtained in 57% yield. Deprotection of (10) was performed with Pd(PPh3)4 and triethylamineHCOOH in a mixture of ethanol and water (according to H. Hey et al., Anew. Chem. Int. Ed. Enql., 12, (1973)928).

The product was purified by recrystallization from acetonitrile and obtained in 77% yield. Three different spacer units (1 Ib), (lIe), and (I If) were prepared by reaction of the corresponding diamine with chloroacetyl chloride in a

mixture of ethyl acetate and water, using potassium carbonate as a base.

These spacers were obtained in 70-79% yield, and characterized by 'H NMR spectroscopy. Finally, the hexaamides (12b,e,f) were prepared via alkylation of (10) with 0.5 mole equivalents of spacer unit 11), a catalytic amount of potassium iodide, and potassium carbonate as a base. Acidic work-up and recrystallization resulted in biscalix[4]arenes (12b,e,f) in # 64% yield, which were pure according to elemental analysis. In all cases, the 2:1 calix[4]arene:spacer ratio was obvious from the integrals in the 1H NMR spectra.

Synthesis of intermediate comnounds <BR> <BR> <BR> <BR> <BR> <BR> 25,26,27-Tris[(N, N-diethylaminocarbonyl)methoxy]-5, ??, 17,23-tetrakis(l, ?- dimethylethyl)-28-(2-propenyloxy)calix[4]arene(9) A mixture of monoallylated calix[4]arene (8) (5.00 g, 7.26 mmoles), potassium carbonate (5.0 g, 36 mmoles), a catalytic amount of potassium iodide, and 2-chloroN,N-diethylacetamide (2.70 ml, 26.2 mmoles) in acetonitrile (300 ml) was refluxed overnight. After cooling to room temperature, the salts were filtered off and the acetonitrile was evaporated.

The crude product was taken up in dichloromethane (200 ml), washed twice with a saturated aqueous solution of ammonium chloride (250 ml) and twice with water (250 ml), and was subsequently dried over magnesium sulfate.

Recrystallizationfrom acetonitrilegave pure (9) in 57% yield. Mp: 93-950C. <BR> <BR> <BR> <BR> <BR> <BR> <P>25,26,27- Tris[(N, N- die th ylaminocarbonyl)meth ox y]- 5,11,17, 23-tetrakis(1, 1- dimeThyleThyi)calx-/4]arnne (10) A mixture of (9) (3.00 g, 2.92 mmoles), triethylamine'HCOOH (0.52 g, 3.50 mmoles), Pd(PPh3)4 (0.25 g, 0.22 mmole) in ethanol (60 ml) and water (12

ml) was refluxed for 2 h. After cooling to room temperature, the solvents were evaporated and the crude product was taken up in chloroform (50 ml). The organic layer was washed twice with a saturated aqueous solution of ammonium chloride (50 ml) and twice with water (50 ml). After drying over magnesium sulfate and evaporation of the solvent, the crude product was recrystallized from acetonitrile (20 ml). Compound (10) was obtained as a white powder in 77% yield. Mp: 225-227°C.

General procedure for the preparation of spacer units (11) A solution of chloroacetyl chloride in ethyl acetate (20 ml) was added dropwise to a mixture of the appropriate diamine and potassium carbonate in ethyl acetate and water. The reaction mixture was stirred overnight, and the precipitate was filtered off. The product was washed with cold ethyl acetate and dried under vacuum. Compounds (11) were used as such.

N, N'-Bis(chlornmeThy1)carbonyi- 1, 4-diaminobenzene (1 Ib) The reaction was performed using chloroacetyl chloride (8.63 ml, 0.11 mole) 1,4-phenylenediamine(4.05 g, 37 mmoles), and potassium carbonate (25.6 g, 0.18 mmole) in a mixture of ethyl acetate (200 ml) and water (200 ml), and gave product (1 Ib) in 79%.

N,N'-Bis(chloromethyI)carbonyl-?, 4-diaminobutane (11 e) Spacer (lIe) was synthesized from chloroacetyl chloride (5.28 ml, 68 mmoles) 1,4-diaminobutane (2.28 ml, 22.7 mmoles), and potassium carbonate (14.5 g, 0.10 mole) in a mixture of ethyl acetate (150 ml) and water (150 ml), and was obtained in 72% yield.

N, N'-Bis(chlornmethy0carbonyi- 1, 6-diaminobutane (I If) The reaction was carried out using chloroacetyl chloride (4.28 ml, 55 mmoles), 1,6-diaminohexane (2.00 g, 17.2 mmole), and potassium carbonate (10.5 g, 76 mmole) in ethyl acetate (60 ml) and water (60 ml), leading to (1 If) in 70% yield.

General procedure for the oreparation of hexaamide biscalixr47arenes 2b, e, f A mixture of (10), potassium carbonate, a catalytic amount of potassium iodide, and 0.5 mole equivalents of (11) in acetonitrile was refluxed for 16 hours. After cooling to room temperature, the solvent was evaporated and the crude product was taken up in dichloromethane (50 ml). The resulting mixture was washed with a saturated aqueous ammonium chloride solution (50 ml) and subsequently with water (50 ml). Compounds (2b,e,f) were dried over magnesium sulfate, and the solvent was evaporated.

The following compounds were prepared: <BR> <BR> <BR> <BR> <BR> <BR> 1, 4-Bis(25-[(aminocarbonyl) methoxy]-26, 27, 28-tris[(N, N- <BR> <BR> <BR> <BR> <BR> <BR> diethylaminocarbonyl)methoxy]-5, 11,-17, 23-tetrakis(l, ?- dimethylethyl)calix[4]arene)benzene (2b) The reaction of spacer unit (11 b) (67 mg, 0.25 mmole) with (20) (0.50 g, 0.51 mmole) in the presence of potassium carbonate (0.09 g, 0.65 mmole) was performed in acetonitrile (25 ml). After work-up and recrystallization from cetonitrile, (2b) was obtained as a white powder in 65% yield. Mp: 293- 2950C.

1,4-Bis{25-[(aminocarbonyl)methoxy]-26,27,28-tris[(N,N- diethylaminocarbonyl)methoxy]-5,11, - 17,23-tetrakis(1,1- dimethylethyl)calix[4]arenegbutane (2e) The reaction was performed using (lIe) (68 mg, 0.28 mmole), 20 (0.56 g, 0.57 mmole), and potassium carbonate (83 mg, 0.68 mmole) in acetonitrile (25 ml). Recrystallization from a mixture of acetonitrile and dichloromethane (20:1) gave (22e) as a white powder in 64% yield. Mp: 263-2650C.

1,6-Bis{25-[(aminocarbonyl)methoxy]-26,27,28-tris[(N,N- <BR> <BR> <BR> <BR> diethylaminocarbonyl)methoxy]-5, 11,-I 7, 23-tetrakis(1, I- <BR> <BR> <BR> <BR> <BR> <BR> dimethylethyl) calix[4]arene)hexane(2f) The coupling was carried out using (ill) (6.9 mg, 2.9 mmoles), 20 (51 mg, 51 mmoles), potassium carbonate (7.5 mg, 54 mmoles), and acetonitrile (15 ml). Recrystallization from methanol gave (2f) as a white powder in 68% yield. Mp: 237-2390C.

Example 3 Synthesis of asymmetric biscalix[4]arenes 3b,e,f (Scheme 3) General description of the synthesis By combination of triethyl ester monoacid chloride (7) (R = tert-butyl) and tris(diethyl)acetamide (12) functionalized with a primary amine, non- symmetric biscalix[4]arenes were prepared. For this synthesis, the tert- butyloxycarbonyl-protectedspacers (15d) and (15f) were synthesized, in the same way as spacer units (11), from a mono-tert-butyloxycarbonyl-protected diamine and chloroacetyl chloride in a 1:1 ratio. The products were subsequently purified by flash column chromatography.

Spacers (15) were used in the alkylation of (12). This alkylation reaction was carried out in a 1:1 ratio, as described before.

Deprotection of (13), leading to the primary amine was performed by passing hydrochloric acid gas through a solution of (13) in dichloromethane. The products were obtained in nearly quantitative yields after evaporation of the solvent and purification by trituration with acetonitrile. The amines were coupled in a 1:1 fashion to monoacid chloride derivative (7), using the same conditions as were employed for the formation of hexaesters. These non- symmetric biscalix[4jarenes were recrystallized from dichloromethane and methanol. Moreover, derivative (3d), which is linked via the shorter spacer, required also Sephadex column chromatography to remove the tetraester (4) formed as side product.

Synthesis of intermediate compounds N-[(Chloromethyl) carbonyq-N(I, I -dimethylethoxy) carbonyl]- 1,3- diaminopropane (15d) The tert-butyloxycarbonyl-protected spacers (15) were synthesized as described for spacer units (21), using chloroacetyl chloride (0.56 ml, 7.2 mmoles) in ethyl acetate (3 ml), and a mixture of N-(tert-butyloxycarbonyl- 1,3-propanediamine (1.00 g, 5.7 mmoles) and potassium carbonate (3.2 g, 23 mmoles) in ethyl acetate (20 ml) and water (20 ml). The solution was stirred for 3 h at room temperature and the organic layer was separated and dried over magnesium sulfate. After purification by column chromatography (3% methanol in dichloromethane), (15d) was obtained as a yellow powder in 82% yield.

N-[(Chloromethyl) carbonyl]-N'-[(1,1 -dimethylethoxy) carbonyl]- 1,6- diaminohexane(15f) Compound (1 5fl was prepared in the same way as described for (1 5d), using a solution of chloroacetyl chloride (1.55 ml, 20 mmoles) in ethyl acetate (8 ml), and a mixture of N-tert-butyloxycarbonyl-l ,6-hexanediamine(4.00 g, 16 mmoles) and potassium carbonate (8.88 g, 64 mmoles) in ethyl acetate (50 ml) and water (50 ml). Column chromatography (3% methanol in dichloromethane)gave (15f) in 75% yield.

25,26,27- Tris[(N, N-diethylaminocarbonyl)methoxy]-28-[(1,1 - dimethylethoxy) carbonyji- 1 -amin o- propyl-3-[(aminoca rb on yl)meth ox y]- 5,11,17,23-tetrakis(1,1-dimethylethyl)calix[4]arene (13d) The alkylation was carried out in the same way as described for hexaamide biscalix[4]arenes (2), using (10) (2.00 g, 2.02 mmoles), (23d) (0.56 g, 2.23 mmoles), potassium carbonate (0.34 g, 2.42 mmoles), a catalytic amount of potassium iodide, and acetonitrile(100 ml). After evaporation of the solvent, (13d) was obtained as a foam in 58% yield, and was used as such for further reactions.

25,26,27- Tris[(N, N-diethylaminocarbonyl)methoxy]-28-[(1,1 - dimethylethoxy)carbonyl]- 1-amino-hexyl-6-[(aminocarbonyl)methoxy]- 5,11,17,23-tetrakis(1,1-dimethylethyl)calix[4]arene(13f) The alkylation was carried out in the same way as described for biscalix[4]arenes (2), using (10) (2.00 g, 2.02 mmoles), (15f) (0.65 g, 2.22 mmole), potassium carbonate (0.34 g, 2.42 mmoles), a catalytic amount of potassium iodide, and acetonitrile(100 ml). Compound (I 3f) was obtained as a foam in 62% yield and was used for further reactions without purification.

25-[1 -A minopropyl-3- (amin ocarb on yl)meth ox y]-26, 27, 28-tris[(N, N '- diethylaminocarbonyl)me-thoxy]-5,11,17,23-tetrakis(1,1- dimethylethyl)calix[4]arene(14d) Hydrochloric acid gas was led through a solution of (13d) (0.94 g, 0.78 mmole) dissolved in dichloromethane (45 ml) for 30 minutes. The solvent was evaporated, and the white residue was triturated with acetonitrile to give compound (14d) in nearly quantitative yield. Mp: 127-1290C.

25-[1 -AminoheXyl-6-(aminocarbonyl)methoxyl-26,27,28-tris[(N, N <BR> <BR> <BR> diethylaminocarbonyl)me-thoxy]-5, ??, 17,23-tetrakis(?, ?- <BR> <BR> <BR> <BR> <BR> dimethylethyl)calix[4]arene(1 4f) Compound (14f) was obtained in the same way as described for (14d), using hydrochloric acid gas, and (13f) (1.55 g, 1.25 mmoles) dissolved in dichloromethane (35 ml). After trituration with acetonitrile, a white powder was obtained in nearly quantitative yield . Mp: 133-1340C.

The following compounds were prepared: 1-{25-[(Aminocarbonyl)methoxy]-26,27,28-tris[(N,N- diethylaminocarbonyl)methoxy]-5,11,17,23-tetrakis(1,1- dimethylethyl)calix[4]arene}-3-{25-[(aminocarbonyl)methoxy]- 5,11,17,23- tetra-kis(1,1-dimethylethyl)-26, 27,28- tris[(ethoxycarbonyl)methoxy]calix[4]arenepropane (3d) The coupling reaction was performed in the same way as described for hexaesters (1), using (7) (0.25 g, 0.26 mmole) dissolved in dichloromethane (20 ml) and a solution of (14d) (0.29 g, 0.26 mmole) and triethylamine (77 pI, 1.0 mmole) in dichloromethane (10 ml). The product was purified by

recrystallization from dichloromethane/methanol, followed by Sephadex (LH20/methanol) column chromotography. Compound (3d) was obtained as a white solid in 70% yield. Mp: 120-1220C.

1-{25-[(Aminocarbonyl)methoxy]-26,27,28-tris[(N,N- diethylaminocarbonyl)methoxy]-5,11,17,23-tetrakis(1,1- dimethylethyl)calix[4]arene}-6-{25-[(aminocarbonyl)methoxy]- 5,11,17,23- <BR> <BR> <BR> <BR> tetra-kis(I, 1-dimethylethyl)-26, 27,28- <BR> <BR> <BR> <BR> <BR> tris[(ethoxycarbonyl)methoxy]calix[4]areneexane (3f) The non-symmetric, double calix[4]arene was prepared in the same way as described for (3d), using (7) (0.25 g, 0.26 mmole) dissolved in dichloromethane (20 ml), and a solution of (14f) (0.30 g, 0.26 mmole) and triethylamine(77,ul,1.0 mmole) in dichloromethane(10 ml). Purification gave a white solid in 68% yield. Mp: I06-1080C.

Example 4 Lanthanide ion complexation General methods Different methods were used to complex Eu3+ ions inside biscalix[4]arenes.

In all cases, biscalixt4larenewas dissolved in acetone, acetonitrile, or either of these solvents in combination with dichloromethane. Subsequently, two equivalents of a Eu(NO3)36H2O were added, followed by stirring overnight either at room or at reflux temperature. The white solids were collected either by precipitation or by evaporation of the solvents. Luminescence studies revealed that hexaester (1tub) does not complex any Eu3+ ions, since stirring in acetone at room temperature only resulted in "free" Eu3+ ions in solution.

Moreover, the precipitate that was collected after refluxing overnight in acetonitrile did not show any detectable luminescence, indicating the absence of Eu3+ ions. On the other hand, all preparation methods that were carried out to prepare Eu3+ complexes of the hexaamide (2b) were successful. However, the highest yield was achieved in refluxing acetonitrile.

In addition, biscalixt4]arene (2b) was complexed with one equivalent of Eu3+ and one equivalent of Nd3+ by the same method. The biscalix[4]arene showed a slight selectivity for Nd3+ as was revealed by the ionic distribution of 1:1.3 determined by X-ray fluorescence.

Eu3+ Complexation I,: 1) dissolve calix[4]arene in acetone, add two equivalents of Eu(NO3)3 in acetone (stock solution), stir overnight, evaporate solvent, dry under vacuum.

2) dissolve calix[4]arene in dichloromethane/acetonitrile (1:1), add two equivalents of Eu(NO3)3 in acetonitrile, reflux overnight, collect precipitate, dry under vacuum.

(2b): 1) dissolve calix[4]arene in acetone/dichloromethane (3:1), add two equivalents of Eu(NO3)3 in acetone, stir overnight, a) evaporate solvent orb) remove solvent with pipette, dry under vacuum.

2) as 1) reflux overnight, collect precipitate, dry under vacuum.as 2) in acetonitrile.1, 4-Bis[25-aminocarbonyl-26, 27, 28-tris[(N, N- diethylaminocarbonyl)methoxy]-5,11,17,23-tetrakis(1,1- dimethylethyl)calix[4]arene]benzenedieuropium(111) hexanitrate(-) (2b'2[Eu(N07) A homodinuclearcomplex (2b2[Eu(NO3)3]) was prepared by method 3, using biscalix[4]arene (22b) (0.108 g, 49.9 simoles) and a stock solution of 19.9 mM Eu(NO3)36H2O (5.02 ml, 99.9 pmoles) in acetonitrile.

Mp: >3000C.

1,4-Bis[25-aminocarbonyl-26,27,28-tris[(N,N-diethylaminoc arbonyl)methoxy]- 5,11,17,23-tetrakis-(1,1-dimethylethyl)calix[4]arene]benzene europium(lll) neodymium(lll) hexanitrate(-) (2b [Eu(NO3)P[Nd(NOs A heterodinuclear complex (2b[Eu(NO3)3][Nd(NO3)3]) was prepared by method 3, using biscalix[4]arene22b (58.2 mg, 26.9 pmoles) stock solutions of 6.14 mM Eu(NO3)36H2O (4.39 ml, 26.9 µmoles), and 6.71mM Nd(NO3)3SH2O (4.01 ml, 26.9,umoles) in acetonitrile. Mp: >3000C.

Example 5 Photophysical studies The photophysical properties of dinuclear complexes (2b Eu2) and (2b Eu Nd) were studied in chloroform, acetonitrile, tetrahydrofuran (THF), and methanol. The solubility of the complexes was low, and so the solutions contained solid particles that caused scattering. The luminescence spectra of the chloroform, acetonitrile, and THF solutions show the typical 5Do o 7Fj transitions at 590, 615, 650, and 695 nm, after ligand-mediated excitation at 300 nm, and direct excitation at 393 nm. The relative intensities of the emission after 300 nm and 393 nm are dependent on the solvent and the concentration. Generally, direct Eu3+ excitation is more efficient than ligand- mediated excitation, which might be a result of the large distance between the aromatic sensitizing units of the calix[4]arene and the Eu3+ ion. On the other hand, the complexes behave completely differently in methanol, as is indicated by the red shift of the most intense emission band to 624 nm. This emission band has a shoulder at 614 nm, at which the peak maximum is usually positioned. Furthermore, two additional emission bands are present at 570 and 600 nm, whereas the band at 580 nm is broadened. The band around 680 nm is also red shifted in methanol-d4. The deviating Eu3+

emission, which was not observed for other Eu3+ complexes that were studied, is very sensitive to small amounts of water and can disappear completely, resulting in the usually observed Eu3+ luminescence.

The presence of Nd3+ in (2bEuNd) was obvious from the typical Nd3+ emission band at 1060 nm that was observed after ligand-mediated excitation. Moreover, luminescence lifetime measurements were performed with the same solutions, and the results are reported in the Table. The lifetimes of (2b Eu2) dissolved in chloroform and acetonitrile are equal within the experimental error, whereas the Eu3+ luminescence is deactivated slightly more efficiently in THF. Upon addition of water, the Eu3+ luminescence is extinguished in both acetonitrile and THF. The lifetime of the complex is relatively short in methanol-d4, and the solution contains a large fraction of Eu3+ ions that have a long lifetime (1.9 ms), which may correspond to free Eu3+ ions in solution. This is supported by the presence of a short-lived component in non-deuterated methanol (0.13 ms). In methanol, a different complex seems to exist from the one in the other solvents that were used.

The most striking feature of the results reported in the Table is the lifetime decrease of the Eu3+ luminescent state after excitation at 300 nm when Nd3+ is present. Based on literature examples, it was expected that the decay curve would be bi-exponential, since the composition of the complex is, in principle, statistical. However, only a mono-exponential decay curve was observed in all solvents. A mixture of the homo- and heterodinuclear complexes also decayed mono-exponentially, the lifetime corresponding to that of the homodinuclear complex. The relative lifetime decrease is most pronounced in acetonitrile and the E values given in Table 1 are equal to the efficiency of energy transfer if this is the only additional deactivation pathway compared to the homodinuclear complex.

Table 1 Lifetimes (in ms) of the 5Do state of (2b Eu2) and (2b Eu Nd) in different solvents, after excitation at 300 nm and detection at 614 nm.a EuEu EuNd CHCl3 1.02 0.50 51 CH3CN 0.93 0.32 66 THF 0.74 0.29 61 CD3ODC 0.39d 0.38 <1 CH30HC 0.26e j a) Data fitting of the decay curves all show two components, one correspondingto the complex and the other to solid particles present ( 0.10 ms); b) relative decrease of the lifetime; c) detected at 624 nm; d) contains a large fraction with a lifetime of 2.5 ms; e) contains a large fraction with a lifetime of 0.1 ms; t) signal too weak.