the disclosure described herein is directed to dyes for use with commercially available ink - jet printers such as design jet ® liner printers , manufactured by hewlett - packard company , of palo alto , calif . more specifically , a specific dye for formulating the magenta is disclosed . the dye enables the production of high - quality print and excellent lightfastness . the inks formulated according to the disclosure produce images having color appearance that meets commercial requirements for color accuracy and durability . one of the more stable photographic systems on the market today is fuji film and print media , which is reported to have a display life of 60 years . a search of patents by fuji revealed that they have developed a novel class of dyes , which when used in photographic media , were very stable . structures 1 and 2 are examples of such dyes : recognizing that the environment around the dye plays a large role in dye stability , hp isolated the magenta dye from developed fuji crystal archive photographic media and investigated its stability on a typical glossy ink jet medium . it was found not to be very stable toward light . further , it is known that these azopyrazolone dyes can be attacked by ozone at the imine carbon . thus , at first glance , this class of dye does not appear to be very interesting from an ink jet application standpoint . however , given that the chemistry of this class of dye is well known and it has a very good color , it is an excellent choice to pursue the concept of steric protection . if all of the large “ ballast ” groups are stripped away that are present in typical photographic dyes to leave the basic chromophore and attach groups to provide steric protection of the imine carbon , the dyes shown in structures 3 and 4 are produced : in structure 3 , the phenyl group attached to the imino n at c - 4 has ortho - methyl groups , which will inhibit formation of tetrahedral n during ozonolysis . similarly , the c - 5 nitrogen has two phenyl groups with ortho chlorines attached to make approach to c - 5 more difficult . in an analogous manner , the azopyrasolotriazole dye ( structure 2 ) has been modified to produce structure 4 . in addition to the same ortho - methyl groups on the imino phenyl ring , oxygen at c - 8 has an isopropyl instead of an ethyl group . molecular modeling ( hyperchem ) of structure 3 shows that the approach to the imine carbon ( or to the entire pyrazolone ring ) is very hindered . structure 1 shows the energy minimized structure . a remaining challenge is to make these dyes water - soluble . two options appear likely . one is to sulfonate one or more of the aromatic rings . second is to change the acetamide groups to contain a water - solubilizing group , such as cooh , so 3 h , or polyether . further , it has been reported that spiroindane compounds when added to solutions of these dyes improve their lightfastness . it is speculated that the spiro materials act as singlet excited state quenchers . thus , similar type additives could be added to these dyes either in the ink or in the media itself . such work is the subject of a recent patent application by the same inventor , u . s . patent application ser . no . 09 / 662 , 950 filed on sep . 15 , 2000 . another approach to providing steric protection of dyes is to encase them inside some structure . one method of doing this is to construct bridges that cross over above and below the imine or azo plane . however , synthetically , such structures are very challenging to make . an alternate method of doing this is to use the concept of “ self - assembly ”. in this approach , the dye is constructed so that it contains arms that spontaneously form bridge like structures . this area of chemistry is extensive and recently reviewed . the driving force to make the bridge structure is the formation of several hydrogen bonds , although other methods such as metal chelation are also possible . using a proto - typical acid azo dye , complementary arms can be attached so that they form hydrogen bonds with each other . this process forms the protecting bridge . such a structure is shown in structure 5 , where the cyanuric and melamine groups can form h - bonds to each other above and below the plane of the naphthalene ring . this effectively “ encapsulates ” the dye . space filling models ( hgs ) show that this arrangement is possible . wherein m and n are from 0 to 4 added carbons . an alternate approach to this methodology is to shorten the alkyl chains that attach the cyanuric acid groups . this precludes intra - molecular h - bonding to the melamine group , but allows inter - molecular h - bonding . a head to tail stacking of the dye molecules then results . this enforced aggregation of the dye protects the dye for obvious steric reasons . further , dye aggregation has been shown to improve light stability . this stacked structure is shown in structure 6 . the present magenta aqueous ink compositions each include , in general , from about 0 . 1 to about 6 wt % of at least one dye , preferably from about 0 . 5 to about 4 wt % of at least one dye , and a vehicle including the following components ( in wt % of total ink composition ): from about 5 to about 30 wt % of at least one organic solvent ; 0 to about 2 . 0 wt % of at least one component independently selected from the group consisting of surfactants , buffers , biocides , and metal chelators ; and the balance water . all concentrations herein are in weight percent of total ink composition unless otherwise indicated . the purity of all components is that employed in normal commercial practice for ink - jet inks . the inks of the present disclosure include an aqueous vehicle including the following components ( in wt % of total ink composition ): from about 5 to about 30 wt % of at least one water soluble organic solvent ; 0 to about 2 . 0 wt % of at least one component independently selected from the group consisting of surfactants , buffers , biocides , and metal chelators ; and the balance water . the inks of the present disclosure include from about 5 to about 30 wt % organic solvent . more preferably , the inks include from about 8 to about 20 wt % organic solvent , with a concentration from about 9 to about 15 wt % being the most preferred . the water soluble organic solvents suitably employed in the present ink - jet ink compositions include any of , or a mixture of two or more , of such compounds as nitrogen - containing heterocyclic ketones , such as 2 - pyrrolidone , n - methyl - pyrrolid - 2 - one ( nmp ), 1 , 3 - dimethylimidazolid - 2 - one , and octyl - pyrrolidone ; diols such as ethanediols , ( e . g ., 1 , 2 - ethandiol ), propanediols ( e . g ., 1 , 2 - propanediol , 1 , 3 - propanediol , 2 - ethyl - 2 - hydroxy - methyl - 1 , 3 - propanediol , ethylhydroxy - propanediol ( ehpd ), butanediols ( e . g ., 1 , 2 - butanediol , 1 , 3 - butanediol , 1 , 4 - butanediol ), pentanediols ( e . g ., 1 , 2 - pentanediol , 1 , 5 - pentanediol ), hexanediols ( e . g ., 1 , 6 - hexanediol , 2 , 5 - hexanediol , 1 , 2 - hexanediol ), heptanediols ( e . g ., 1 , 2 - heptanediol , 1 , 7 - heptanediol ), octanediols ( e . g ., 1 , 2 - octanediol , 1 , 8 - octanediol ); glycols and thioglycols , commonly employed in ink - jet inks , such as polyalkylene glycols such as polyethylene glycols ( e . g ., diethylene glycol ( deg ), triethylene glycol , tetraethylene glycol ), polypropylene glycols ( e . g ., dipropylene glycol , tripropylene glycol , tetrapropylene glycol ), polymeric glycols ( e . g ., peg 200 , peg 300 , peg 400 , ppg 400 ), and thiodiglycol ; and glycol ethers such as dipropylene glycol monobutyl ether , propylene glycol monobutyl ether , and ethylene glycol monobutyl ether , diethylene glycol monohexyl ether . the inks of the present disclosure optionally include 0 to about 2 . 0 wt % surfactant . more preferably , the inks include from about 0 . 1 to about 1 . 8 wt % surfactant , with a concentration from about 0 . 8 to about 1 . 5 wt % being the most preferred . in the practice of the disclosure , one or more surfactants may optionally be used . non - ionic surfactants , such as secondary alcohol ethoxylates ( e . g ., tergitol series available from union carbide co . ), non - ionic fluoro surfactants ( e . g ., fc170c available from 3m , non - ionic fatty acid ethoxylate surfactants ( e . g ., alkamul psmo - 20 available from rhone - poulenc ), non - ionic silicone surfactants ( e . g ., silwetl7600 available from osi specialties , inc . danbury , conn . ), and fatty amide ethoxylate surfactants ( e . g ., aldamide l203 available from rhone - poulenc ) are preferred , with secondary alcohol ethoxylates being the most preferred . in the practice of the disclosure , the surfactant serves to prevent color to color bleed by increasing the penetration of the inks into the print medium , and to improve the spread of the ink on polymer coated media . secondary alcohol ethoxylates are nonionic surfactants and are commercially available , for example , from union carbide co . ( houston , tex .) as the tergitol series , such as tergitol 15 - s - 5 and tergitol 1 5 - s - 7 . the secondary alcohol ethoxylates contain ( a ) an aliphatic chain having a prescribed number of carbon atoms in the chain , and ( b ) a prescribed number of ethoxylated units . these ethoxylates are commercially available as mixtures of ethoxylates , and so are described in terms of the predominance of a given compound . secondary alcohol ethoxylates suitably employed in the practice of the disclosure predominantly have from about 12 to about 18 carbon atoms in the aliphatic chain , while the number of ethoxylated units is predominantly in the range of from about 4 to about 8 units . thus , “ tergitol 15 - s - 5 ” represents a secondary alcohol ethoxylate surfactant predominantly having about 15 carbons in its aliphatic chain and about 5 ethoxylated units . tergitol 15 - s - 5 and tergitol 15 - s - 7 are the preferred surfactants . the inks of the present disclosure optionally include 0 to about 1 . 5 wt % buffer . more preferably , the inks include from about 0 . 1 to about 0 . 5 wt % buffer , with a concentration from about 0 . 1 to about 0 . 3 wt % being the most preferred . buffers employed in the practice of the disclosure to modulate ph can be organic - based biological buffers or inorganic buffers , preferably , organic - based . further , the buffers employed should maintain a ph ranging from about 3 to about 9 in the practice of the disclosure , preferably about 6 . 5 to about 8 and most preferably from about 7 . 5 to 8 . 5 . examples of preferably - employed buffers include trizma base , available from companies such as aldrich chemical ( milwaukee , wis . ), 4 - morpholinoethanesulfonic acid ( mes ), b - hydroxy - 4 - morpholinepropanesulfonic acid ( mopso ), and 4 - morpholinepropanesulfonic acid ( mops ). the inks of the present disclosure optionally include 0 to about 1 . 5 wt % metal chelator . more preferably , the inks include from about 0 . 1 to about 0 . 5 wt % metal chelator , with a concentration from about 0 . 1 to about 0 . 3 wt % being the most preferred . metal chelators employed in the practice of the disclosure are used to bind transition metal cations that may be present in the ink . examples of preferably - employed metal chelators include : ethylenediaminetetraacetic acid ( edta ), diethylenetriaminepentaacetic acid ( dtpa ), trans - 1 , 2 - diaminocyclohexanetetraacetic acid ( cdta ), ( ethylenedioxy ) diethylenedinitrilotetraacetic acid ( egta ), or other chelators that can bind transition metal actions . more preferably , edta , and dtpa ; and most preferably edta in its disodium salt form is employed in the practice of the disclosure . the inks of the present disclosure optionally include 0 to about 1 . 5 wt % biocide . more preferably , the inks include from about 0 . 1 to about 0 . 5 wt % biocide , with a concentration from about 0 . 1 to about 0 . 3 wt % being the most preferred . any of the biocides commonly employed in ink - jet inks may be employed in the practice of the disclosure , such as nuosept 95 , available from huls america ( piscataway , n . j . ); proxel gxl , available from zeneca ( wilmington , del . ); and glutaraldehyde , available from union carbide company ( bound brook , n . j .) under the trade designation ucarcide 250 . proxel gxl is the preferred biocide . the specific ink set disclosed herein is expected to find commercial use in ink - jet color printing . a pyrazolone azomethine dye of the present disclosure , is synthesized as shown below : the desired hindered phenylenediamine is made by treating 2 , 5 - dimethyl - 1 , 4 - phenylenediamine with methyl - 3 - chloropropanante and hydrolyzing the resulting ester to the acid . in the above formula , the pyrazolone azomethine dye [ 4 -( 3 - methyl - 4 -) 4 -( n , n - di -( ethylsulfonic acid ) amino )- 1 - phenylimino )- 5 - oxo - 2 - pyrazolin - yl )- benzoic acid ] was prepared by adding 0 . 6 grams of potassium persulfate to a stirred mixture of 4 -( 3 - methyl - 5 - oxo - 2 - pyrazolin - 1 - yl )- benzoic acid ( 1 mmol ), n , n - di - ethylsulfonic acid )- 1 , 4 - phenylenediamine ( 0 . 25 g ), methanol ( 10 ml ), and sodium carbonate in water ( 5 %; 20 ml ). the mixture was stirred for about 40 minutes and then additional water ( 70 ml ) was added . the pyrazolone azomethine dye was collected by filtration , dried and recrystallized with methanol or ethanol . while several embodiments have been described in detail , it will be apparent to those skilled in the art that the disclosed embodiments may be modified . therefore , the foregoing description is to be considered exemplary rather than limiting .