AU2004200554B2 - Electroactive Compounds - Google Patents

Description

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-1-

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant/s: University College Dublin Actual Inventor/s: Donald Fitzmaurice and David Cummins and David Corr and Nagaraja S. Rao and Gerrit Boschloo Address for Service: Baldwin Shelston Waters MARGARET STREET SYDNEY NSW 2000 CCN: 3710000352 Invention Title: ELECTROCHROMIC DEVICE Details of Original Application No. 76816/00 dated 11 Oct 2000 The following statement is a full description of this invention, including the best method of performing it known to me/us:- File: 34908AUP01 500304015 1.DOC/5844

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-la- ELECTROACTIVE COMPOUNDS This invention relates to electroactive compounds. In particular, it relates to electroactive compounds which may be chemisorbed to a nanostructured metal oxide film, doped to metallic levels of conductivity. Such films are used in electrodes and electrochromic devices comprising such electrodes.

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

The use of electrochromic devices in applications where optical modulation is required, such as large area static displays and automatically dimmable rear-view mirrors, is well known. Electrochromic devices comprising at least one electrode incorporating a semiconducting nanostructured metal oxide film modified by chemisorption of an electroactive compound are also known, see for example WO-A-97/35227 and WO-A-98/35267.

The device disclosed in WO-A-97/35227 comprises an nor p-type redox chromophore chemisorbed at the surface of a nanostructured semiconductor electrode, and an auxiliary electroactive compound of the p- or n-type, respectively, which can be oxidised or reduced in a reversible manner, is dissolved in the electrolyte. In the device disclosed in WO-A-98/35267 an n-type redox chrompohore is chemisorbed at the surface of a nanostructured semiconductor electrode and a p-type redox promoter is dissolved in the electrolyte.

Although the switching time of these devices is more rapid than that of previously known devices, it is still relatively slow due to the rate-limiting step being the diffusion of the electroactive compound in electrolyte to the relevant electrode. Attempts to eliminate this rate-determining step by adsorbing this compound to the electrode to which it diffuses have only resulted in moderate increases in the rate of switching due to the semiconducting nature of the nanostructured substrate.

While the devices disclosed in WO-A-97/3522 7 and WO-A-98/35267 are adequate for the applications mentioned above, more rapid switching times would be desirable, especially where dynamic displays, privacy glazing and-smart windows are concerned.

It is an object of the invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

As used herein, the term "electroactive compound" refers to those compounds which are adsorbed at the surface of a conducting nanostructured metal oxide film and are oxidised. If these compounds change colour on being oxidised, they are referred to as p-type redox chromophores. If they do not change colour, they are referred to as p-type redox promoters; and those compounds which are adsorbed at the surface of a semiconducting or conducting nanostructured metal oxide film and are reduced. If these compounds change colour on being reduced, they are referred to as n-type redox chromophores. If they do not change colour, they are referred to as n-type redox promoters.

According to the invention there are provided compounds of the formulae V, VI and VII I Fe

VII

vi wherein X in formula V is S or 0 and R 8 are each independently selected from the following: (HO)2 P-(CH2)n- (HO)2P-(CH2)nO0 HO(CHi2)n- HOOC(0H2)n- (HO)2B(CH)n- (R1 O)3Si (CH)n 0 0 HO-it i aCH 2 )ff-C-O-(CH 2)n-

HO*

0

HO-Q_

P (C O

NH-(CH

2 )rwherein R 11 is C 1 -i 0 alkyl and n 1-10, excluding acetic acid ferrocene and hydroxyethylferrocene.

The invention also provides electrodes and electrochromic devices comprising compounds of the general formulae V, VI and/or VII.

Compounds of the general formula V can be prepared by reacting phenothiazine with an alkyl halide terminated with the precursor to or a suitable linker group.

Compounds of the general formula VI can be prepared by reacting an alkyl substituted dihydro-dialkyl phenazine with an alkyl halide terminated with the precursor to or a suitable linker group.

Compounds of the general formula VII can be prepared by reacting a suitably derivatized ferrocene with an alkyl halide terminated with the precursor to or a suitable linker group.

A particularly preferred p-type redox promoter of the general formula V is P-(10-phenothiazyl) propoxy phosphonic acid. This compound (compound VIII) can be prepared according to reaction scheme 1 hereinafter.

Unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising', and the like are to be construed in an inclusive sense as opposed to an 4a exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".

The invention is illustrated in the following Examples.

EXAMPLE 1 A 2.5 cm x 2.5 cm transparent nanostructured semiconductor film, consisting of a 4 pm thick layer of fused Ti02 nanocrystallites, was deposited on a 3.3 cm x 3.3 cm fluorine doped tin oxide on glass substrate (15 9, 0.5 pm thick, Libby-Owen Ford Tec 15). A colloidal Ti0 2 dispersion was prepared by hydrolysis of titanium tetraisopropoxide. The average diameter of the initially formed crystallites (7 nm) was increased by autoclaving at 200 0 C for 12 hours to 12 nm.

Concentrating the autoclaved dispersion to 160 g/l and adding Carbowax (Trade Mark) 20000 (40% wt. equiv. of Ti0 2 yielded a white viscous sol. (Carbowax 20000 is an ethylene glycol polymer whose average molecular weight is 20000.) A 4 Am thick layer of the above sol was deposited using a screen printing technique on the conducting glass substrate. The resulting gel-film was dried in air for 1 h, sintered in air at 450 0 C for 12 h and stored in a darkened vacuum desiccator prior to use. The resulting transparent nanostructured electrodes were 4 Am thick and had a surface roughness of about 1000.

An n-type redox chromophore, bis-(2phosphonoethyl)- 4,4'-bipyridinium dichloride was prepared by adding 4,4'-bipyridine (4.4 g) and diethyl- 2-ethylbromo-phosphonate (15.0 g) to water (75 ml).

The reaction mixture was refluxed for 72 h and allowed to cool. Following addition of conc. hydrochloric acid ml) the reaction mixture was refluxed for a further 24 h. To recover the product, the reaction mixture was concentrated to 50 ml, isopropyl alcohol (200 ml) added drop-wise, stirred on ice for one hour and filtered.

The white crystalline product was washed with cold isopropyl alcohol and air dried to give pure bis-(2phosphonoethyl)-4,4'-bipyridinium dichloride (12.72 g, 84.24 yield). Calculated for bis-(2-phosphonoethyl)- 4,4'-bipyridinium dichloride (C 14

H

20

N

2 C1 2 0 6

P

2 C, 37.77; H, 4.53; N, 6.29. Found: C, 35.09; H, 4.49; N, 6.09. 1 H NMR (water-d 2 8 2.31-2.43 (m,4H); 5 4.68-4.80 4H); 8 8.33 unresolved metacoupling, 4H); 6 8.94 unresolved metacoupling, 4H).

TiO 2 films, prepared as described above, were modified by chemisorption of a monolayer of the n-type redox chromophore, also prepared as described above, from an aqueous solution (0.02 mol.dm 3 over 24 h, washed with distilled isopropanol, dried in air and stored in a darkened vacuum desiccator for 48 h prior to use.

A 2.5 cm x 2.5 cm transparent nanostructured SnO 2 :Sb film was prepared on a 3.3 cm x 3.3 cm F-doped tin oxide glass substrate (15 2, 0.5 pm thick, supplied by Libby-Owen Ford Tec 15) largely as described in "Spectroscopy of Highly Doped Nanostructured Tin Dioxide Electrodes" The Journal of Physical Chemistry, 1999, 103, pp 3093-3098, G.

Boschloo and D. Fitzmaurice. Briefly, 10 drops of acetic acid (2.0 mol dm 3 were added with stirring to an aqueous dispersion (50 g) of 5 nm diameter Sb-doped SnO, nanocrystals (15% by wt.SnO,:Sb, supplied by Alfa).

The gel which formed immediately was diluted by addition of water (15 ml) and autoclaved at 200 0 C for 12 h. Addition of Carbowax 20000 (3.75 g) with stirring for 8 h yielded an amber viscous paste which was diluted with water (10 ml) to make it suitable for spreading. This paste was spread using a glass rod on the conducting glass substrate masked by Scotch tape.

Following drying in air for 1 h the film was fired, also in air, at 450 0 C for 12 h. The resulting transparent nanostructured SnO,:Sb films were 3.0 pm thick and had a surface roughness of about 1000.

The p-type redox promoter VIII was prepared as shown in Scheme 1, as follows: XI: -(10-phenothiazyl) propionitrile Triton B (benzyl trimethylammonium hydroxide; 0.6 ml of a 40% aq. soln.) was added dropwise to a solution of phenothiazine 50 g) in acrylonitrile (45 ml) on ice resulting in a vigorous reaction. The reaction mixture was refluxed for 1 h and allowed to cool. The resulting crude product was recrystallized from a 30:70 mixture of hot ethanol and acetone to yield orange crystals of XI, (31.27 g, 49.6%).

XII: #-(10-phenothiazyl) propionic acid The compound XI (31.27 g) was added to a mixed solvent (350 ml methanol, 105 ml water) NaOH (35 g) solution, refluxed for 15 h and allowed to cool. The crude product was poured on ice water and acidified by the addition of sulphuric acid (2 mol dm 3 until a white precipitate formed. The crude product was recrystallised to yield XII, (17.0 g, 52.26%).

XIII: P-(10-phenothiazyl) propionate ester The compound XII (17 g) was dissolved in 1:2 by vol.

mixture of ethanol and toluene (700 ml) acidified by addition of cone. sulphuric acid (4 ml) and refluxed overnight. The solution was concentrated (to approximately 50 ml) and diluted by addition of water (500 ml). The crude product was extracted in ethyl acetate (4 x 200 ml), washed with water, dried over

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MgSO,, filtered and the solvent removed under reduced pressure. White crystals of XIII precipitated from the solution on cooling, (11.85 g, 63.9%).

XIV: f-(10-phenothiazyl) propanol A solution of the compound XIII (11.85 g) in dry diethyl ether (33 ml) was added dropwise to a suspension of LiAlH, (4.74 g) in dry diethyl ether ml) and stirred overnight at room temperature. Excess LiAlH, was decomposed by the dropwise addition of water and filtered. Removal of the solvent under reduced pressure gave the green solid XIV, (5.57 g, 54.7%).

XV: f-(10-phenothiazyl) propoxy phosphonic acid dichloride A solution of XIV (1.0 g) and pyridine (1.0 ml) in dry chloroform (60 ml) was cooled to -15 OC. A solution of phosphorous oxychloride (4.73 ml) and pyridine (1.0 ml) and dry chloroform (40 mls) was added dropwise over h. The reaction mixture was stirred at -15 "C for 2 h and the resulting homogeneous solution allowed to reach ambient temperature over 1.5 h. The chloroform was removed under reduced pressure and the crude product washed with toluene (3 x 50 ml) to remove any unreacted phosphorous oxychloride affording a green oil XV, (0.9 g, 65.2%).

VIII: f-(10-phenothiazyl) propoxy phosphonic acid A solution of XV (0.9 g) in deionised water (60 ml) was stirred overnight. The crude product was extracted in ethyl acetate (4 x 50 ml), washed with water, dried over sodium sulphate. The white crystals that formed were removed by filtration and the filtrate recrystallized a further 3 times to yield the product VIII, (0.301 g, Calculated for VIII (C 5

H,

6 0,NSP): C, 53.43; H, 4.76; N, 4.15; P, 9.19. Found: C, 63.58; H, 5.42; N, 4.77; P, 1.86. 1 H NMR (CDCl 3 d 2.24-2.28 (t 2H, J=6.3 Hz); d 3.67-3.70 2H, J=6.2 Hz); d 4.09-4.12 2H, Hz); d 6.91-7.19 8H). "P NMR (CDC1,): d 1.69-1.89 (H 3 d -11.96 nanostructured SnO 2 :Sb films, prepared as described above, were modified by chemisorption of a monolayer of the p-type redox promoter VIII, also prepared as described above, from a chloroformic solution (0.02 mol dm 3 during 6 h, washed with distilled isopropanol, dried in air and stored in a darkened vacuum desiccator for 24 h prior to use.

A cell, with an internal spacing of about 400 pm, was constructed from a modified TiO, film and a modified SnO 2 :Sb film prepared above using a thermoplastic gasket (IPBOND 2025, supplied by Industria Plastica Monregalese). This gasket had an opening at one corner.

The sandwich structure was evacuated in a modified vacuum desiccator, dipped with the opening in the electrolyte solution, and filled by admitting air into the vacuum desiccator. The electrolyte solution consisted of LiClO 4 (0.02 mol dm in y-butyrolactone.

It should be noted that both the LiCIO0 and y-butyrolactone were carefully purified and rigorously dried prior to use. Finally, the cell was sealed using a UV-curable epoxy resin.

SCHEME 1 0.(1-N H NC

HOOC

X X1 jii (d) aNNO a N p0 OH

OCH-

2 CH1 3

CI-P

Cd 0\ XV Ai Vx111 I(h)

HIO-P

HO 0 Vill Reagents and conditions for synthesis for Scheme 1 (VII): Acrylonitrile, 40% aq. solution benzyl trimethylammoniumn hydroxide (Triton 00 C Reflux 1 h Methanolic sodium hydroxide, Reflux 15 h.

Ethanol, conc. 112S04, Reflux overnight.

LiAIH1 4 Diethyl. ether (dry) Phosphorous oxychioride, stir, -15' C for 2 h Stir for 1.5 h to bring to ambient temperature 1120 EXAMPLE 2 Switching Times of Electrochromic (EC) Window The rate of colouration of the 2.5 cm x 2.5 cm EC window assembled as described in Example 1 was measured following application of a voltage of 1.2 V which biased the viologen modified nanostructured TiO 2 film negative of the phenothiazine modified SnO 2 :Sb film.

The colouration time, defined as the time taken for the transmittance to decrease by two-thirds of the difference between the steady-state transmittances in the bleached and coloured states, was about 450 ms. The rate of bleaching of the same EC window was measured by reversing the polarity of the voltage applied to the previously coloured device. The bleaching time, defined as the average time taken for the transmittance to increase by two-thirds of the difference between the steady-state transmittances in the coloured and bleached states, was about 250 ms.

The measured colouring and bleaching times are, as far as the inventors are aware, the fastest switching times reported for EC windows of this area.

Colouration Efficiency of EC Window The peak and steady state currents of the 2.5 cm x cm EC window were also measured during colouring and bleaching. The peak and steady-state currents measured on colouring were approximately 10 mA cm 2 and approximately 30 pA cm 2 respectively. The peak and steady-state currents measured on bleaching the same EC window were approximately 16 mA cm' and approximately 1 A cm 2 respectively. The colouration efficiency CE(X) at 550 nm, defined by Equation was determined from the slope of the plot of the increase in absorbance

I

AA(1) versus the charge accumulated in the device AQ.

The measured CE (550 nm) was approximately 110 C 1 cm 2 CEI (1)

SAQ

Both the above peak and steady-state currents are very low and suggest that the power consumption of the EC window will be low and that it should have a long-term memory.

Concerning power consumption, the 2.5 cm x 2.5 cm EC window prepared in Example 1 will have an associated steady-state current of approximately 30 pA in the coloured state. This implies that the rate of charge consumption is approximately 2.4 x 10 3 Cs or approximately 1.5 x 1016 electrons s 1 Concerning the long-term memory, if a voltage of 1.2 V is applied to the EC window for 60 s and the circuit opened, the EC window first colours and then bleaches on the time-scale of hours. More quantitatively, the absorbance of the EC window measured at 608 nm takes about 3 h to return to the initially measured value, while the time required for the minimum transmittance in the coloured state to increase by 5% is 600 s.

Stability of EC Window The stability of the 2.5 cm x 2.5 cm EC window prepared in Example 1 was tested under ambient conditions by subjecting it to 10,000 electrochromic cycles. Each electrochromic cycle consisted of applying a potential of 1.2 V, which biases the viologen modified nanostructured TiO, electrode negative of the phenothiazine nanostructured SnO,:Sb electrode, for

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s and applying a voltage of 0.00 V for 15 s. The parameters used to characterise cell performance were measured after 1, 10, 100, 1,000 and 10,000 electrochromic cycles and are summarised in Table 1.

TABLE 1: Stability of Window under Electrochromic Cycling Number of Electrochromic Cycles 1 10 100 1,000 10,000 Transmittance in Bleached State 64 61 67 57 64 Transmittance in Coloured State 13 12 17 14 23 Colouring Time (ms) 460 443 605 448 422 Bleaching Time (ms) 245 270 215 265 212 Peak Colouring Current (mA cm") 10 12 7 12 9 Peak Bleaching Current(mA cm 16 17 17 12 11 Steady-State Coloured Current 33 28 17 13 (pA cm 2 Steady-State Bleached Current 1 2 1 2 1 (pA cm 2 Colouration Efficiency cm) 110 110 110 110 105 This test was performed under ambient conditions on a 2.5 cm x 2.5 cm device assembled in Example 1.

as described Each electrochromic cycle involved applying a voltage of 1.2 V which biased the viologen modified nanostructured electrode negative of the phenothiazine modified electrode for 15 s and then applying a voltage of 0.0 V for 15 s.

Another aspect of the stability, is the period over which it is possible to maintain the EC window in a coloured state. This aspect of the stability was examined by applying a voltage of 1.2 V, which biases the viologen modified nanostructured TiO 2 electrode negative of the phenothiazine nanostructured SnO 2 :Sb electrode, and which causes the device to colour. This voltage was applied for 15 s and, having determined that the time required for the minimum transmittance to increase by 5% is 180 s, this potential was applied for s every 180 s. This maintained the EC window in the coloured state throughout. It was found that there was no significant degradation after 500 h.

Generally, the findings summarised in Table 1 establish that a 2.5 cm x 2.5 cm EC window assembled as described in Example 1 is relatively stable under ambient laboratory conditions over 10,000 electrochromic cycles while the findings summarised above establish that the same window is stable in the coloured state for 500 h.

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EXAMPLE 3 Preparation of -(10-phenothiazyl) propyl-phosphonic acid (illustrated in Scheme 2) Steps of Scheme 2 are described in relation to Scheme 1 in Example l(e).

XVa: P-(10-phenothiazyl) propyl-phosphonate #-(10-phenothiazyl) propyl chloride IX (5 g, 1.8 x 10-2 M) was refluxed in 5 equivalents of triethyl phosphite for 48 h. The unreacted triethyl phosphite was removed by vacuum distillation to yield the crude product XVa which was taken to the next step without further purification.

H NMR (chloroform-d): 6 1.17-1.22 6H, J=7.1 Hz), 6 1.79-1.92 2H), 6 2.03-2.13 2H), 8 3.92-4.14 6H), 6 6.84-7.17 8H, aromatic) XVI: /-(10-phenothiazyl) propyl phosphono-trimethyl silyl ester To an ice cold solution of XVa (0.15 g, 4 x 10-'M) in CHC1, (dry) was added a cold solution of bromotrimethylsilane (0.18 g, 1.2 x 10 M) in CHC1, (dry).

The reaction mixture was stirred (0 1 h) and then at room temperature for 16 h. The solvent was removed under reduced pressure to yield the crude silyl ester XVI which was taken to the next step without further purification..

'H NMR (chloroform-d): 6 0.00-0.39 18H), 6 1.75-

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1.90 (in, 2H) 8 2.00-2.20 (mn, 2H1), 3.84 2H1), 6.80-7.20 (in, 811, aromatic) XVII: 3- (10-phenothiazyl) propyl-phosphonic acid XVI was stirred in a mixture of 1,4-dioxane: H 2 0 (1:1) at room temperature for 2h. The resulting precipitate was filtered and dried to yield the crude product XVII ~H NMR (methyl sulphoxide-d,): 8 1.55-1.67 (in, 211), 81.78-1.84 211), 8 3.91-3.96 211, J=7.0 Hz), 86.8-7.3 (in, 811, aromatic) SCHEME 2 (XI)

(XII)

(iv) 04 OH (xiv) OCH1 2

CH

3

(XIII)

(v)

(XV)

P

HO-P

HO 0

(VIII)

(V O(SZ Ci, ,-OCH 2

CH

3 )0 oCH 2

CH

3 (XVa) \(vii) POH P HOS IH 3 3 (XVII)

(XVI)

Reagents and conditions for synthesis for Scheme 2 (XVI): acrylonitrile, Triton B (40% aq. solution), 00C; reflux 1 h (ii) methanolic sodium hydroxide, reflux 15 h; (iii) ethanol-toluene, conc. H 2

SO

4 reflux 12 h; (iv) diethyl ether (dry), LiAH 4 pyridine-chioroform (dry), phosphorous oxychioride, stir, -15' C, 2 h; stir, RT, 1.5 h; (vi) triethyl phosphite, reflux, 48 h (vii) dry chloroform, OOC; bromotrimethyl silane, dry chloroform, OOC; stir, RT, 16 h (viii) 1,4-Dioxane/H 2 0 stir, RT, 2 h.

EXAMPLE 4 Preparation of P-(10-phenothiazyl) propionate phosphonic acid (illustrated in Scheme 3) XXVI: 3-(10-phenothiazyl) propionitrile To an ice cold solution of phenothiazine (XXV, 50g) in acrylonitrile (45 mL) was added Triton B (0.6 mL of a 40% aq. soln.). After some time a vigorous reaction took place. The reaction mixture was heated on a steam bath for 2 h and allowed to cool. The resulting crude solid was crystallized from a 30:70 mixture of hot ethanol and acetone to yield orange crystals of xXVI.

XXVII: 3-(10-phenothiazyl) propionic acid The compound XXVI (20 g) was refluxed for 15 h in 450 mL of methanolic sodium hydroxide(methanol:water, 350:105 mL). The crude product was poured into ice water and acidified by the addition of sulfuric acid (2 mol dm' 3 The crude product was crystallized from ethanol to yield XXVII.

'H NMR (chloroform-d): 6 2.66-2.67 2H, J=7.9 Hz); 6 4.04-4.09 2H, J=7.9 Hz); 8 6.76-7.05 8H, aromatic) XXVIII: f-(lO-phenothiazyl) propionic acid chloride XXVII (1.0 g) was refluxed in 10 mL of oxazyl chloride for 3 h. Removal of oxazyl chloride under low pressure afforded the crude acid chloride XXVIII which was taken for the next step without further purification.

'H NMR (chloroform-d): 8 3.40-3.45 2H, J=7.9 Hz); 3 4.27-4.32 2H, J=7.9 Hz); 6 6.87-7.25 8H, aromatic) XXIX: #-(lO-phenothiazyl) propionate phosphate ester XXVIII (1.0 g) was dissolved in dry chloroform containing a small quantity of pyridine. Diethyl hydroxy methylphosphonate was added and the reaction mixture was stirred at room temperature overnight.

Removal of the solvent under reduced pressure yielded the crude product XXIX which was taken to the next step without further purification.

'H NMR (chloroform-d): 8 1.32-1.37 2H, J=7.9 Hz); 6 2.93-2.98 2H, J=7.9 Hz); 8 4.12-4.28 6H, J=7.9 Hz); 8 4.41-4.44 2H, J=7.9 Hz); 8 6.89-7.22 8H, aromatic) XXX: f- (10-phenothiazyl) propionate phosphonotrimethyl silyl ester To an ice cold solution of XXIX (1.0 in CHC1, (dry) was added a cold solution of bromo-trimethylsilane (0.18 g, 1.2 x 10-' M) in CHC1, (dry). The reaction mixture was stirred (0 OC, 1 h) and then at room temperature for 16 h. The solvent was removed under reduced pressure to yield the crude silyl ester XXX which was taken to the next step without further purification.

H NMR (chloroform-d): 5 0.00 18H); 6 2.93-2.98 2H); 8 4.23-4.26 4H, J=7.9 Hz); 5 7.11-7.19 (in, 8H, aromatic) XXXI: 3- (1 0-phenothiazyl) propionate phosphonic acid xxx (0.1 g) was stirred in a mixture of 1,4-dioxane: H 2 0 at room temperature for 2h. The resulting precipitate was filtered and dried to yield the crude product XXXI.

1 H NM~R (methyl sulphoxide-d): 8 2.93-2.98 (mn, 2H1); 8 4.23-4.26 (in, 4H1); 8 7.11-7.19 (in, 8H1, aromatic) SCHEME 3 III

H

2 0=CHCN- K 1L)- K~ K J NON N

H$$

(XXV) (XXVI) (iii)OOC (XXVII) N(v 04 (XXX) pOs(H (vi) 0 4'r 0 K~0 OH

(XXXI)

QOH

2 H IXVIII 00

(XXIX)

Reagents and Conditions Triton B, OOC, 2h;reflux 2h (11) NaOH, CH 3 OH, reflux (iii) Oxazyl chloride, reflux 3h (iv) Diethyl hydroxy methylphosphonate, dry CHCI 3 I Pyridine, stir r.t.

Bromotrimethylsilane, dry CHC1 3 000, stir r.t. 1 6h (vi) 1 ,4-Dioxanel H 2 0 stir r.t. 2h EXAMPLE Preparation of (1-Ferrocenyl) imido-benzylmethyl phosphonic acid (illustrated in Scheme 4) XXXII: (1-Ferrocenyl) imino-benzyldiethylphosphonate Ferrocene aldehyde (2.5 g, 1.1 x 10- 2 M) was dissolved in toluene (80 mL). 4-amino benzyl phosphonate (2.6 g, 1.2 x 10-2 M) and a catalytic amount of para-toluene sulphonic acid (0.13 g) was added and the reaction mixture was refluxed for 3 h, in a Dean-Stark setup.

The solvent was concentrated under reduced pressure, to yield the crude product XXXII which was taken through to the next step without further purification.

IH NMR (chloroform-d): d 1.25-1.3 6H, J=7.0 Hz), d 3.13-3.20 2H, J=21 Hz), d 3.98-4.09 4H, Hz), d 4.26-4.83 9H), d 7.12-7.33 (dd, 4H, aromatic), d 8.35 1H) XXXIII: (1-Ferrocenyl) imido-benzyldiethylphosphonate To a warm (50 0 C) solution of XXXII (5.39 g, 1.2 x 10- 2 M) in methanol (80 mL) was added solid NaBH, (0.5 g, 1.2 x 10 2 A vigorous reaction occurred and the reaction mixture was refluxed for 3 h. The reaction mixture was cooled to room temperature stirred for 16 h. The solvent was removed under reduced pressure, and the crude product was taken up in chloroform (4 x mL) and dried. The chloroform layer was washed with water and dried. Removal of the solvent afforded the crude product which was purified using column chromatography (100% CHC1,) to yield XXXIII.

IH NMR (chloroform-d): d 1.25-1.30 6H, J=7.0 Hz), d 3.04-3.11 2H, J=21 Hz), d 3.99-4.05 4 H, Hz), d 4.05-4.26 11H), d6.62-6.65 2H, aromatic), d 7.13-7.16 2H, aromatic) XXXIV: (1-Ferrocenyl) imdio-benzyldiethyl trimethylsilyl ester To an ice cold solution of XXXIII (1.0 g, 2 x 10' 3 M) in CHC1, (dry, 10 mL) was added a cold solution of bromotrimethylsilane (2.0 g, 1.3 x 10- 2 M) in CHC1, (dry, 4 mL). The reaction mixture was stirred (0 OC, 1 h) and then at room temperature for 16 h. The solvent was removed under reduced pressure to yield the crude silyl ester XXXIV which was taken to the next step without further purification.

'H NMR (chloroform-d): d 0.00 18H), d 2.94 2H, J=21 Hz), d 4.17-4.19 11H), d 6.79-6.85 2H, aromatic), d 7.09-7.20 2H, aromatic) XXXV: (1-Ferrocenyl) imido-benzylmethyl phosphonic acid XXXIV was stirred in a mixture of DMF/ H 2 0 at room temperature for 4 h. The crude product that precipitated was filtered, washed with H,0 and dried under vacuum to yield XXXV.

IH NMR (methyl sulphoxide-d,); d 2.71-2.78 2H, J=21 Hz), d 3.93-4.26 11H), d 6.53-6.55 2H, J=7.9 Hz), d 6.92-6.95 2H, J=7.1 Hz) "P NMR (methyl sulphoxide-d,): d 24.4 SCHEME 4 0 H -H 2 ,,0 HH2 C= C- C-F-OCCHH- Fe +HN& CI1C-3Fe

OCH

2

CH

3

OCH

2

CH

3

I

(XXXII)

H

2

H

2 0(i) 4 H N C-R, -OSi(CH 3 )a 3 Fe HOSi(CH 3 Fe H

OCH

2

CH

3 (XXX(IV) (XXXIII)

H

2

H

2

,,O

C-N /C-R\-0H H

OH

Fe

(XXXV)

Reagents and Conditions Toluene, para-toluene suiphonic acid, reflux 4h (ii) Sodium Borohydride, CH 3 OH, reflux 3h (iiii) Bromnotrimethylsilane, dry CHCI 3 Q 0 O0.5h; r.t. 12h (iv) Dimethylformarnide/ H 2 0 r.t. 4h EXAMPLE 6 Preparation of f-(10-phenoxazyl) propionate phosphonic acid (illustrated in Scheme XIX: 8- (10-phenoxazyl) propionitrile To an ice cold solution of phenoxazine (XVII, 50g) in acrylonitrile (45 mL) was added Triton B (0.6 mL of a 40% aq. soln.). After some time a vigorous reaction took place. The reaction mixture was heated on a steam bath for 2 h and allowed to cool. The resulting crude solid was crystallized from a 30:70 mixture of hot ethanol and acetone to yield orange crystals of XIX.

XX: /-(lO-phenoxazyl) propionic acid The compound XIX was refluxed for 15 h in 450 mL of methanolic sodium hydroxide(methanol:water, 350:105 mL). The crude product was poured into ice water and acidified by the addition of sulfuric acid (2 mol dm-3). The crude product was crystallized from ethanol to yield XX.

1H NMR (chloroform-d): 6 2.74-2.80 2H, J=7.9 Hz); 6 3.90-3.96 2H, J=7.9 Hz); 6 6.54-6.88 8H, aromatic) XXI: f-(lO-phenoxazyl) propionic acid chloride XX (1.0 g) was refluxed in 10mL of oxazyl chloride for 3 h. Removal of oxazyl chloride under low pressure afforded the crude acid chloride XXI which was taken for the next step without further purification.

'H NMR (chloroform-d): 6 3.19-3.28 2H, J=7.9 Hz); 6 3.90-3.99 2H, J=7.9 Hz); 6 6.47-6.90 8H, aromatic) XXII: f-(10-phenoxazyl) propionate phosphate ester XXI (1.0 g) was dissolved in dry chloroform containing a small quantity of pyridine. Diethyl hydroxy methylphosphonate was added and the reaction mixture was stirred at room temperature overnight. Removal of the solvent under reduced pressure yielded the crude product XXII which was taken to the next step without further purification.

'H NMR (chloroform-d): 6 1.35-1.42 6H, J=6.9 Hz); 6 2.77-2.82 2H, J=7.3 Hz); 6 3.91-3.96 2H, J=7.6 Hz); 8 4.11-4.28 4H); 6 4.41-4.44 2H,J=8.8 Hz), 6 6.55-6.87 8H, aromatic) XXIII: #-(1O-phenoxazyl) propionate phosphonotrimethyl silyl ester To an ice cold solution of XXII (1.0 in CHC1, (dry) was added a cold solution of bromo-trimethylsilane (0.18 g, 1.2 x 10 M) in CHC1, (dry). The reaction mixture was stirred (0 OC, 1 h) and then at room temperature for 16 h. The solvent was removed under reduced pressure to yield the crude silyl ester XXIII which was taken to the next step without further purification.

'H NMR (chloroform-d): 6 0.0 18H); 6 2.65-2.70 (t,

I

2H, J=7. 6 Hz) 6 3.8 0 86 (in, 2 H) 5 4. 2 5-4. 36 2H, J=10.0 Hz); 6 6.44-6.80 (in, 8H, aromatic) XXIV: f-(1O-phenoxazyl) propionate phosphonic acid XXIII (0.1 g) was stirred in a mixture of 1,4-dioxane: HO0 at room temperature for 2h. The resulting precipitate was filtered and dried to yield the crude product XXIV.

HNMYR (methyl sulphoxide-d) 62.60-2 .67 (mn, 4H), 8 3.66-4.20 2H, J=7.0 Hz), 66.49-6.86 (in, 8H, aromatic) 31 P NMR (methyl sulphoxide-d 6 24.5

I

SCHEME N H 2 C=HNiL H NC HOOC (XX)

(XVII)

(XIX)

(v)

N

04 0 K OSi(CH 3 3 O~Si(CH 3 3 0: I (vi 0 C0 0

(XXIII)

(XXII)

(XXI)

0

OH

H(XXIV)

Reagents and Conditions Triton B, 000, 2h;reflux 2h (Ii) NaOH, CH 3 OH, ref lux (111) Oxazyl chloride, reflux 3h iv) Diethyl hydroxy methyiphosphonate, dry CHC1 3 1 Pyridine, stir r.t.

Bromotrimethylsilane, dry CHC1 3 000, stir r.t. 16h (vi) 1 ,4-Dioxane/ H 2 0 stir r.t. 2h

I

EXAMPLE 7 Stability Tests Preparation of Nanostructured Electrodes: All glass was thoroughly cleaned prior to use. Each sheet was manually cleaned using detergent which was thoroughly rinsed off using water. This was then washed with acetone to remove all water present and the acetone was evaporated using hot air. Each film was deposited using a doctor-blading technique. An adhesive stencil was placed over each glass electrode giving the required geometry necessary to leave a perimeter of mm. The glass surface was cleaned with iso-propanol and air-dried prior to deposition. A deposit of sol was placed at one end of the glass and manually drawn to the opposite end of the glass with a glass rod (7 mm diameter) leaving an even deposit of the sol. The cathode was a 50mm x 50mm square TEC 15 glass sheet with nanoporous nanocrystalline titanium dioxide (prepared as in Example 1 except that the films were dried with hot air and sintered in air for 1 h) coated on an area of 40mm x 40mm square at the centre of the window, leaving an exposed one half centimetre perimeter for sealing materials. The anode was a x 50mm square TEC 15 glass sheet with nanoporous nanocrystalline antimony doped tin oxide (prepared as in Example 1 except that the films were dried with hot air and sintered for 1 h) coated on an area 40mm x square at the centre of the window, leaving an exposed one half centimetre perimeter for sealing materials.

Modification of Nanostructured Electrodes Prior to being modified with the redox compound, the nanostructured cathodes and anodes were placed in an oven at 350 °C to remove any water vapour or organic material. The electrodes were allowed to cool to approximately 80 °C before being placed into the redox compound solutions. All cathodes consisting of a nanostructured TiO 2 working electrode were modified by chemisorption of the viologen bis-(2-phosphonoethyl)- 4,4'-bipyridinium dichloride from an aqueous solution (1 x 10- 2 mol dm containing 0.1 M LiClO, over a 2 h period. Following the derivatisation process, each film was placed horizontally in a wash bath of ethanol for one minute. The washed, derivatised electrodes were dried using hot air.

All anodes consisting of antimony doped tin oxide electrodes were derivatised with a series of six redox promoters giving six sets of six windows as outlined below: Set A: No redox promoter chemisorbed onto the antimony doped tin oxide electrodes Set B: A solution of f-(10-phenoxazyl) propionate phosphonic acid as prepared in Example 6 (ca. 1 x 10' 3

M

in acetonitrile and 6 x 10- 3 M LiPF,) were prepared and six windows were immersed for two hours in this solution.

Set C: A solution of i-(10-phenothiazyl) propoxy phosphonic acid as prepared in Example l(e) (ca. 1 x 3 M in acetonitrile and 6 x 10 3 M LiPF,) was prepared and six windows were immersed for two hours in this solution.

Set D: A solution of E-(10-phenothiazyl) propylphosphonic acid as prepared in Example 3 (ca. .1 x 10-' M in chloroform and 6 x 10' 3 M LiPF,) was prepared and six windows were immersed for two hours in this solution.

Set E: A solution of #-(10-phenothiazyl) propionate phosphonic acid as prepared in Example 4 (ca. 1 x 10 3

M

in chloroform/acetonitrile and 6 x 10- 3 M LiPF,) was prepared and six windows were immersed for two hours in this solution.

Set F: A solution of (1-ferrocenyl) imido-benzylmethyl phosphonic acid as prepared in Example 5 (ca. 1 x 10 M in 1:1 chloroform:dimethyl sulfoxide and 6 x 10- 3

M

LiPF,) was prepared and six windows were immersed for two hours in this solution.

Following the derivatisation process, each film was placed horizontally in a wash bath of the respective solvent it was modified from, for one minute. The washed, derivatised electrodes were dried using hot air. The windows were sealed immediately after dying.

The cathode and anode were sandwiched together with the electrodes placed in an offset configuration with 2-3 mm offset on two opposite sides to provide an area for an external ohmic contact.

The switching times and stability of each device (A-F) were tested as described in Example 2. The results are shown in Tables 2-7. Optical absorption spectra were recorded using a Hewlett-Packard 8452A diode array spectrophotometer. A Solartron SI 1287 potentiostat was used to record potential-current characteristics.

All reported testing was done at room temperature.

TABLE 2 Set A No Redox Promoter Number of Electrochromic 1 10 100 1000 3500 7000 Cycles Transmittance in Bleached 69 66 67 68 70 State M% Transmittance in.Coloured 33 31 34 38 46 41 State_% Steady-State Coloured Current 290 330 300 290 270 250 (AA Cnf 2 Steady-State Coloured Current 15 22 21 20 13 23 (pA cM- 2 Colouring Time (ins) 500 500 400 300 300 400 Bleaching Time (ins) 800 800 500 600 300 400 TABLE 3 Set No. B Phenoxazine Numuber of Electrochromic 1 10 100 1000 3500 7000 Cycles Transmittance in Bleached 67 67 67 69 69 69 State M% Transmittance in Coloured 24 25 23 30 32 36 State M% Steady-State Coloured Current 550 2600 440 380 270 180 (pA cm- 2 Steady-State Coloured Current 12 10 16 12 4 (pA cm- 2 Colouring Time (mns) 800 800 800 800 800 900 Bleaching Time (ins) 600 500 600 500 400 400 TABLE 4 Set No. C Phenothiazine (PPPA) Number of Electrochromic 1. 10 100 1000 3500 7000 Cycles Transmittance in Bleached 68 67 67 70 68 68 State Transmittance in Coloured 36 35 35 51 44 46 State M% Steady-State Coloured Current 63 62 76 49 38 34 (pA cm- 2 Steady-State Coloured Current 11 29 29 12 7- (pA cm- 2 Colouring Time (ins) 400 500 600 500 400 500 Bleaching Time (ins) 400 500 600 300 300 400 TABLE Set No. D Alkyl Phenothiazine

(PPP)

Number of Electrochromic 1 10 100 1000 3500 7000 Cycles Transmittance in Bleached 66 66 67 66 66 66 State Transmittance in Coloured 18 18 20 21 24 26 State Steady-State Coloured Current 1060 990 860 610 390 320 (PA crrC 2 Steady-State Coloured Current 10 11 12 15 9 (pA cm~j 2 Colouring Times (ins) 1200 1200 1300 1300 1300 1200 Bleaching Times (ins) 1 500 500 1400 1 500 1 500 1 400 TABLE 6 Set No. E Phenothiazine Ester (PPPE) NUniber of Electrochromic 1 10 100 1000 3500 7000 Cycles_____ Transmittance in Bleached 68 68 67 67 67 68 State M% Transmittance in Coloured 20 18 17 17 18 18 State_% Steady-State Coloured Current 1780 1750 1700 1600 1490 1390 (PA cM- 2 Steady-State Coloured Current 5 9 4 11 13 8 (jIA cm- 2 Colouring Times (mns) 1000 1400 900 800 1000 1000 Bleaching Times (mns) 500 500 600 500 500 500 TABLE 7 Set No. F Ferrocene (Fc) Number of Electrocliromic 1 Cycles Transmittance in Bleached 57 State M% I 4~ r T 1

.LUU

1000 3500 7000 t to I I Transmittance in Coloured 16 13 13 15 21 21 State M% Steady-State Coloured Current 470 270 130 100 (~Acm- 2 Steady-State Coloured Current 11 10 7 9 6 6 (gA cm- 2 Colouring Times (mns) 1000 1400 900 800 1000 1000 Bleaching Times (mns) 500 j500 600 j 500 50050 The tabulated results can be explained as follows: Transmittance in the bleached state the percentage of light passing through the device in the colourless state.

Transmittance in the coloured state the percentage of light passing through the device in the coloured state.

Steady State Current (SSC) the value of the current when it has reached an equilibrium.

Generally, the findings summarised for A-F in Tables 2- 7 establish that a 40 x 40 mm EC window assembled as described above is stable under ambient laboratory conditions over 7000 electrochromic cycles. The values of the transmittance in the colourless state are generally consistent throughout each test indicating that a large proportion of the incident light is passing through each device even after 7000 cycles.

This indicates substantially no optical degradation of the films. The transmittance values in the coloured state are also generally consistent. The dynamic ranges between the transmittance in the colourless state and the transmittance in the coloured state are large which indicate good performance for an EC device.

The SSC values for the coloured state are generally less that 25 micro amps cm 2 This indicates a very small leakage current. The SSC for the bleached state in each case is of the order of 1 micro amp cm 2 These low power consumption readings illustrate the memory effect of the devices as constructed. Furthermore, each device exhibits rapid switching times for both the coloured and colourless states. Colouring times range from 30 to 75 ms/cm 2 and bleaching times from 25 to

I

ms/cm 2 These times are significantly faster than those obtained with conventional devices which have switching times of at least 1 s/cm 2 The advantages of the EC devices herein over previous EC devices are: 1. They are fast switching.

2. They provide deeper colouration.

3. The range of colours is greater.

4. They have low steady state current.

This application is a divisional of Australian Patent Application No. 76816/00 the entirety of which is incorporated herein by cross-reference.

Claims (6)

1. A compound of any of the formulae V, VI or VII ~L2~2~-Rio Fe wherein X in formula V is S or 0 and R 8 are each independently selected from the following: P? (HO)2 P-(CH2)n- R? (HO)2 P-(CH12)nO- HO(CFi2)f- HOOC(CH)n- (HO)2B(CH)f- (Rn O)3Si(CH2)n- O O HO HO-(CH2)nfC-O-(CH 2)n-- HO HO H NH-(CH 2 HO-(CH2)n NH -(CH2)n HO wherein R 11 is C 1 -o alkyl and n 1-10, excluding acetic acid ferrocene and hydroxyethylferrocene.

2. A compound according to claim 1 of the formula V which is selected from p-(10-phenothiazyl) propoxy phosphonic acid; p-(10-phenothiazyl) propyl-phosphonic acid; p-(10-phenothiazyl) propionate phosphonic acid; and p-(10-phenoxazyl) propionate phosphonic acid.

3. A compound according to claim 1 of the formula VII which is (1-ferrocenyl) imido-benzylmethyl phosphonic acid.

4. An electrode or electrochromic device comprising a compound according to any of claims 1 to 3.

5. A compound substantially as herein described with reference to any one of the embodiments of the 42 invention illustrated in the accompanying drawings and/or examples.

6. An electrode or electrochromic device substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples. DATED this 2 9 t day of April, 2005 Shelston IP Attorneys for: UNIVERSITY COLLEGE DUBLIN