A C T A U N I V E R S I T A T I S L O D Z I E N S I S ____________________FOLIA CHIM1CA 3 , 19B4__________________
J o a n n a Masłowska, Longin C h r u ś c iń s k i
CKRÜMIUM(III) COMPLEXES WITH EL-METHIONINE AND L-CYSTEINE*
Chrom ium (III) complexes w i t h DL~methionine and L -c y - s t e i n e have beon i n v e s t i g a t e d by p H -m etric and s p e c t r o - p h o to m e tr ic m ethods. I n b o th i n v e s t i g a t e d s y s te m s , t h r e e complexes o f t h e c o m p o s itio n H : L » 1 : 1; 1 : 2 ; 1 : » 3, have been found, s t a b i l i t y c o n s t a n t s f o r t h e r e s u l t a n t complexes have been d e te r m in e d by t h e method o f B jerrum . C r y s t a l l i n e complexes w ith t h e i n v e s t i g a t e d l i g a n d s o f t h e t y p e : [CrtM et)}]. 2tf20 and Na[Cr(Cys),J. 2Hj>0 were a l s o o b t a i n e d . The made c o m b in a tio n o i ( C r ( I I I ) With t h e i n v e s t i g a t e d am ln o acid and s t r u c t u r e s o f t h e complexes r e p o r t e d have been proposed on t h e b a s i s o f t h e i r s p e c t r a . A method f o r p r e c i p i t a t i o n pu re complexes from s o l u t i o n s h a s been d e v is e d u s i n g t h e io n -e x c h a n g e p r o c e s e on t h e r e s i n Sephadex A-25.
I n t r o d u c t i o n
The r o l e o f m eta l i o n s i n t h e b io c h e m ic a l p r o c e s s w ith t h e c o n t r i b u t i o n o f a m in o a cida h a s n o t been f u l l y u n d e rs to o d a s y e t . The r e a c t i o n s b e tw e en a m in o a cid s c o n t a i n i n g su p h u r and t r a n s i t i o n m e t a ls i o n s a r e o f I n t e r e s t i n c o n s i d e r a t i o n o f s t i l l u n u t i l i z e d o p p o r t u n i t i e s o f t h e u se o f t h e s e compounds i n t h e r a p y
m .
I n f o r m a t i o n a b o u t N i ( I I ) , Z n ( I I ) , H g ( I I ) , C d ( I I ) , P b ( I I ) , F e ( I I ) , Mn(II) and C o ( I I ) complexes w it h some a m in o a cid s con t a i n i n g s u l p h u r i s a v a i l a b l e i n t h e l i t e r a t u r e [ 2 - 7 ] . But t h e r e a r e i n s u f f i c i e n t d a t a on t h e C r ( I I I ) complexes w i t h m e th io n in e and c y s t e i n e . S c a r c e i n f o r m a t i o n [8-1.1] c o n c e r n s s o l i d complexes
* P ra c a z o s t a ł a n a d e s ł a n a na I I I p o l s k o - r a d z i e c k i e , , sympozjum "Termodynamika i e le k t r o c h e m i a roztworów e l e k t r o l i t ó w .
o r s t u d i e s on sy ste m s i n t h e p r e s e n c e o f q u i t e a d i f f e r e n t l i gand a s e . g . v i o l e t R.
In th e p r e s e n t s tu d y , s y s te m a tic I n v e s t i g a t i o n s o f th e s y - * stem s: C r ( I I I ) - D L -m ethionine - HgO am? C r ( I I I ) - L - c y s te in e - H^O a r e u n d e rta k e n . They a r e aim ed a t th o ro u g h u n d e rs ta n d in g o f e q u i l i b r i u m r e a c t i o n s in s o l u t i o n s s e p a r a t i o n o f s o l i d complex«* and d e te r m in a tio n o f t h e i r s t r u c t u r e s .
E x p e rim e n ta l
R eag en ts and a p p a ra tu s
The fo llo w in g r e a g e n ts were u s e d : D L -m ethionine ( R e a n a l) , L - c y s t e i n e h y d r o c h lo r id e m onohydrate (M erck ); sodium p e r c h l o r a t e monohydrate (K o c h -L ig h t), 70% p e r c h l o r i c a c id (H opkin and W il* l i a m s ) , sodium h y d ro x id e (FOCh), chromium c h l o r i d e h e x a h y d ra te (BDH), sodium c h l o r i d e (POCh) ?nd DEAE-Sephandex A25 (P h arm acia F i n e ) . A ll t h e r e a g e n ts were o f a n a l y t i c a l g r a d e . The am ino- a c i d s were p u r i f i e d by c r y s t a l l i z a t i o n from agueous - e th a n o llc s o l u t i o n s . Chromium p e r c h l o r a t e was p r e p a r e d a c co x d in g t o R a - s k o and S a l y m o s i [1 2 ]. The c o n c e n t r a t io n o f C r(IX I) was m easured by a re d o x y ra e tric method [1 3 ].
F o r pH m easurem ents, a d i g i t a l N517 pH -m eter (M era-E lw ro) e q uip p ed w ith a g l a s s o Q P-7171-1/A e le c t r o d e and a c a lo m el 0 P - -830 ( R a d e l k i s ) e l e c t r o d e , was u s e d .
A b s o r p tio n e l e c t r o n i c s p e c t r a were re c o rd e d w ith a UV-VIS s p e c t r o p h o t o m e t e r ( C a rl Z e is s J e n a ) . IR s p e c t r a were re c o rd e d on a ¿joecord 71 IR s p e c tro p h o to m e te r o v e r ra n g e 4600-700 cm“ 1 o r a UR-10 s p e c t r o p h o t o m e t e r o v e r t h e ra n g e 700-400 cm , u s in g a KEr p e - l l e t .
P ro c e d u re
Tho r e a c t i o n s i n C r ( I I I ) - L - H^O sy stem s (w h ere L i s • t r .i o n ln e o r c y s t e i n e ) a t room t e m p e r a t u r e p r o c e e s v e ry slow ly. Tha f.-quli iriu m i s re a c h e d w i t h i n a p e r i o d o f 1 m onth, an d , *. r • , an i n v e s t i g a t i n g p ro c e d u re , a s d e s c r ib e d by N a g a
-C r (I I I ) complexes w ith DL-methionino and L -c y ste in e 25
t a and c o -w o rk e rs [1 4 ], was u s e d . So, '40 sam ples o f ?0 cm ' i n volume were p r e p a r e d . They c o n ta in e d v a r io u s amount o f t h e
-»2
i n v e s t i g a t e d am inoacid (from 1*10 J t o 6 - 1 0 m o l e / 1 ) , chromium ( I I I ) s a l t (from 1 . 10~4 to 2 ,5 • 10” 5 m o le/1 ) and NaOH. The i o n i c s t r e n g t h o f a l l th e s o l u t i o n s was c o n s ta n t and e q u a l to 0 .1 (NaClO^). The s o lu t i o n s were s to r e d i n an i n c u b a t o r a t a te m p e ra tu re o f 25 - 0 . 1°C f o r 1 m onth. Then, t h e pH v a lu e s o f t h e s o l u t i o n s were m easured and u se d t o c a l c u l a t e t h e s t a b i l i t y c o n s t a n t s . I n s p e c tr o p h o to m e tr ic m easu rem ents, t h e s o l u t i o n c o n ta in in g C r { I I I ) and am in o acid were h e a te d on a w a t e r b a th f o r 2 h , and th e n t h e i r a b s o r p tio n s p e c t r a w ere re c o rd e d a t room te m p e r a tu r e . A s o l i d com plex o f C r ( I I I ) and L - c y s t e i n e was p re p a re d i n t h e fo llo w in g m anner [ 8 ] . Aqueous s o l u t i o n o f 50 cm^ in volume c o n ta in in g 1 m ilim o le o f CrCl^ and 3 m ilim o - l e s o f L - c y s te in e h y d r o c h lo r id e was h e a te d i n a w a t e r b a t h . When t h e c o lo u r o f t h e s o l u t i o n had been changcd from g r e e n t o r e d - d i s h - v i o l e t , a s o l i d NaOH was ad d ed . At pH a b o u t 7 , d a rk b l u - i s h - r e d c r y s t a l l s o f th e C r ( I I I ) complex w ith L - c y s te in e were p r e c i p i t a t e d . The complex was f i l t e r e d o f f , washed w ith e t h a n o l and d r ie d a t 100°C. The c r y s t a l l i n e complex o f C r ( I I I ) w i t h DL- -m e th io n in e was p re p a re d a c c o rd in g t o M i z u o c h i and c o - -w o rk e rs [1 5 ].
R e s u lts and d i s c u s s io n
S t a b i l i t y c o n s ta n t s o f C r ( I I L ) com plexes w i t h DL-methionine and L - c y s te in e ,
The ch an ges i n t h e v i s i b l e r e f l e c t a n c e s p e c t r a o f t h e i n v e s t i g a t e d sy stem s ( F ig . 1) p o i n t t o t h e f o r m a ti o n o f CrLr com p le x e s . I t was found, by t h e method o f J o b , t h a t t h e complex o f t h e c o m p o s itio n M j L ■ 1 : 3 ( F ig . 2 ) i s a d o m in a tin g one i n bo th sy stem s a t a w a v e len g th X ■ 540 nm. The v a l u e s o f s t a b i l i t y c o n s ta n t s c a l c u l a t e d 'by th e m ethod o f “c o r r e s p o n d in g s o l u t i o n s " [16] a r e g iv e n i n Tab. 1. The T ab le c o n t a i n ? a l s o t h e v a lu e s o f d i s s o c i a t i o n c o n s ta n t s o f D L-m ethionine and L - c y s t e - in e [17].
500 550 500 650 700 Xt nm] X[nm]
F ig . 1 . A b s o r p tio n s p e c t r a o f a 1 • 10~2 M s o l u t i o n o f ( C r CIO*)* w ith v a r i a b l e lig a n d c o n -o eS'cr? -o i-o n -o ^ L )A [1 2 5 i- 2 . 0 ; 4 - 3 . 0 ; 5 - 4 .0 ; 6 - 3 .0 ; 7 - 6 .0 ; 6 - 7 .0 ; 9 -8 . 0 ; 10 - 9 .0 ; 11 — 10j 10 a o l/d .’a^ ; pH = 4 .3 ; d = 2 c n . a - L = L - c y s te in e h y d r o c h l o r id e ; b - L m D L -aieth ionine Jo an n a Ha slo wsk a', L on gi n C h r u fe c ln a lt l
. N * - •
S t a b i l i t y c o n s t a n t s Kn o f c o m o lc x e s C r ( Î I I ) w i t h D L - m e th i o n in e and L - c v s t e i n e fo und by s p e c t r o o h o t o m e t r i c and p o t c n t i o œ e t r i c m ethods
A m i n o a c i d u n d e r i n v e s t i g a t i o n S t a b i l i t y c o n s t a n t s l o g Kn D i s s o c i a t i o n c o n s t a n t s o f a m i n o a c i d Kn s p c c t r c p h o t o m e t r i c m e t h o d p o t e n t i o m e t r i e m e t h o d l o g K 1 l o g K2 lO R K j l o g K1 l o R K2 l o R K 3 P K , p K 2 pK3 D L - m e t h i o n i n e 7 . 4 5 - 0 . 3 0 6 . 5 4 - 0 . 3 0 5 . 9 9 - 0 . 3 0 7 . 9 1 - 0 . 4 5 6 . 9 4 - o . 4 5 6 . 4 3 - 0 . 3 5 2 . 3 2 - 0 . 0 5 9 . 1 5 ^ 0 . 0 5 i L - c y s t e i n e 8 . 0 5 - 0 . 3 0 7 . 4 5 - 0 . 3 0 3 2 - 0 . 3 0 8 . 3 2 - 0 . 4 5 7 . 6 9 - 0 . 4 5 6 . 9 4 - 0 . 3 5 1 . 7 1 - 0 . 0 5 8 . 3 5 - 0 . 0 5 1 0 . 3 6 ^ 0 . 0 5 o e t e t p O V C« o GQ O H- £ O rt < e t 0î P c r ►t c • a P - O e t H* X co « r t o B P M 3* 3 ' M *— P 3" 3 5 H» 3* » n r t t ' H- w- r t H* ►î 3* rr i— e t K- < o H* 3 ►ji SU (b fi> fi /~v P ? r O a P- fi) H* o O r t i - r t a fi) a fi) r t P r t O g c P* U-*.
W O y H 3* C ' fi> M C M r t C ta 3 »-*• c 5 3 ' H* X g M 3 3 *c g Cs}
fî o ** H ' M O h - C0 M *—• K {/) 3 " O fi? 3 3 « W fi/ H* M Co p r t O 3 o H-* t—« *■* *< ?O >-«4 K-*H* "C M p . e tb*"- f h'- O » 3 O Qh m e t 10 3 KH et ►3 t*î c (D <1 o fi) Hi v
M O 3 3 H il p O t J P r X Ci v>‘
P M O * ■ e t I-* e t 3" *d Q r t C P B e t <& O H* Cr r* O O ift fi) M y ;
•w ht *< p H* 3* 3* r t H» »+ C O e t ?T C P H* cr 1 < 3* O r t co CO « *• M ►H CO o O fi> H ’ o 3* O r» f t p ' fî) 3 O H» <d 3 p P - P « ft r* O CD 3 C o P* <Ü O ' 3 p p e t b~ H> M e t P- o H- e t fi) r t M O f) 3 o O CO g rü 3 £ c r O • 3 i t-j C ♦-» 3^ O P *< 3 et- C rt- 3* P r t r t h, H- 3* p 3 r t O o r t 3 x : O 3 O e t ’S fi» 3' cp 3 “ H- 3 o P- H- p H* 3 co r f O to f-J h* O c h-* H- e t O 3* M fi» »— O P pr D (D £ w O n» o3 C r t f t H 1 3* p. Q O x o 2 C+ X O fi) 3 O ►3 < H* O J- £ S' o o O h* 3 *< 3 K-» O e t O P W X 3 O • a P 0Q P r t ft P O e t 3 ri c +1 C 3 O C; P m V- 3* M fi) c »-*• •1 O H* 3' ♦-■•j *y C *î 3 cr r* 3 CXi p. h-* P W C C § H** r t C<t D cr P to rt- ♦-*> H* C C O p (b M0) *“5 P- fr o fo 3' K** P* r t *1 'O O f— O H g* r P e t <5 et O O 3* fi) M 3 G «r. fi. r t B et 03 r t 3 H* O t~*) 3 p 3 O i O O r t CO c tj TD u ro3 3o £ (t> 5" P C' O C o e Ch O P- P . fi H* 3 P HH3' c J * fD Ci rt* fi> 3 *d h^à *5 C W H' O et C0 O p o* co O ou ofi (?) 3 c »-*• C p C ^3 3* et p. cr h** i uw < M C o 3 M jrr *1 C »T- O CD p < r t i-* fi H- îi «*< M H» O ‘O 3 n> H> K •c c O >a H- Cfi ►; H to pV- P O p p f— o
r t fi> m et o Î H# X rt 3* 3; c O O 3 U P >H r t et >--» r 4 C ► c H- r* 3' r* r î O O *1 O c: C o 3* C *r~* p o v: fi) O C M 3' Co C i B *' £3 *< c O r*-* ._ » F O *j M O H* *1 • 3 O t w >• o • W *< fii o -^3 ft C ►j P fî C Vi Ô Ck X o r t »— M en v- M c a. H o c —• (£ >** P Ch s£ es .3 P e t *< *1 Q P p O O Vé fi> o B O 3 H- vo e t r t c r n H* r t M* r t 3* H 3 <r>* P- »-»* H cr fsj O 3 et X o a Hi 3 % h*-H- O '----• 3^ O £*/. c r C <> O P . e* fi> 'J O s 3 ' r. h - 3 P C* V-» 3 O O O Q a 3 c f» o >» ( f 3 * fi) rt> 3 • 3 ” 1 15 3 rt- <d . 1 3 I (5 1 P- « 1 I H» m, 1 a i rr *< S « i 5 C r (I I I ) c o n pl a x e » w ith DL-meth nio nln e an d L -c ys ta in e
F ig . 2 , Assignment u f t h e complex c o m p o sitio n by th e m ethod o f c o n t i n u o u s changes o f J o b . 1 - ( C r I I I ) w ith L -c y 3 te in e } 2 - C r(X II) w i t h D L -m ethionine, C o n c e n t r a t i o n suit * O.Qô M, ,d » 1 cm; X ■ 540 run. A » Am - ; Am « a b so rb a n c e o f th e m ix tu re ,
ACr « a b s o rb a n c e o f t h e Cr(C10^)j
F i g , 3. Tne f o r m a ti o n c u r v e s o f Bjerrum f o r t h e s y s te m s ; C rC III) + D L -m ethionine; o - C r ( I I I ) + L - c y s t e i n e
Cr(III) complexes with DL-nethionine and l-cjstelne 29
T a b l e 2 S t a b i l i t y c o n s ta n t s K„ o f C r ( I I I ) com plexes
w ith some l ig a n d s in an aqueous s o l u t i o n
Ligand lo g K1 lo g K2 lo g Kj ...R e fe re n c es E th y le n e d ia m in e (en) 16.5 14 [18] G ly cin e ( g l i ) 8 .6 2 7 .6 5 - [18] a - a la n ln e ( a l a ) 8.53 7.44 - [18] O x a la te (ox) 5.3** 5.17 - [18] D L-m ethionine (met.) 7 .4 5 6 .5 4 5 .9 9 t h i s s tu d y L - c y s te in e (c y s) 8 .0 5 7.45 6 .3 2 t h i s s tud y form s complexes e a s i e r w i t h l i g a n d s c o - o r d i n a t i n g th ro u g h n i t r o gen and oxygen atom s.
i*
P r e p a r a t i o n and p r o p e r t i e s o f c r y s t a l l i n e complexes o f Cr( i n ) w it h DL^me t h i o n i j i e a n d L- c y s t e i n e
A s o l i d c r y s t a l l i n e complex compound o f C r(IX I) w ith L-cy- s t e i n e and a s o l i d compound o f C r ( I I I ) w i t h DL-methionine wex'e p r e p a r e d a c c o r d in g t o t h e above m e n tio r e d p r o c e d u r e . The rnolacu- l a r form ulae o f t h e two complex compounds were a s s i g n e d on t h e b a s i s o f e le m e n ta l a n a l y s i s . For Na[Cr(L - c y s ) 2]2H20: c a l c u l a t e d ( » ) C 2 0 .4 0 ; H 5 . 1 3 ; 0 2 7 .1 7 ; K 7 . 9 3 ; 3 1 8 .1 5 ; Cr 1'<.72 f o u n d « » ) C 2 0 .5 1 ; H 5 . 3 3 ; 0 2 7 .3 1 ; H 7 . 8 7 ; S 1 8 .0 2 ; Cr 14,65' For [Cr(DL - meth)^}2H20s c a l c u l a t e d (Si) C 3 3 .6 3 ; H 6 . 9 6 ; 0 2 3 .8 9 ; M 7 . 8 3 ; S 1 7 .9 6 ; Cr 9.71 found ( * ) C 3 3 .5 0 ; H 7.C2; 0 2 4 .0 0 ; N 7 . 8 9 ; S 1 7 .8 0 ; Cr 9 .5 8
To know s t r u c t u r e s o f b o th s o l i d com plexes, t h e i r l i t s p e c t r a (T ab. 3 ) and UV-VIS s p e c t r a o f t h e i r s o l u t i o n s (Tab. 4) a- r made.
The s h i f t o f t h e band c o rr e s p o n d in g t o s t r e t c h i n g v i b r a ■.; xs ^(N i^) from 2300 cm"*1 to the. ran g e 3220 - 3120 cm“ 1 i n ;
T a b l e 3 C h a r a c t e r i s t i c a b s o r p t i o n bands i n t h e l it s p e c t r a o f t h e i n v e s t i g a t e d am lnoacids
and t h e i r complexes w i t h C r ( I I I )
OL-M et Band Cr(.Met)52H20 Band L-Cys HC1H20 Band
— --- ---NaCr(Cys)22H20 Band 3000
in
NHL V 3220 m nh2V
3050 m nh2 V 3120 m«a, V
2700is
WH2 Vs 3120 m nh~ Vs 2565 mS-H V
1640 a C»0V
1950 sco
2 Va 1640 scoi
Va 1740 s C=»0V
1610 s C° ; Va 1400 s CO” Vs 1420 s CO' Vs 1230v
3 C-0 V 1560m
NH
2 6 1320 m SCH5V
1320m
SCHj V
1210V„
s C-0V
1260 C-0 V 780 mcs
Va 780 mCS
Va 690 mC-S
V 670C-S
V 685cs
Vs 685 mCS
Vs • 450m
CrN
V-V - s t r e t c h i n g v i b r a t i o n , Vg - sym m etric s t r e t c h i n g v i b r a t i o n , Vfi - asym m etric s t r e t c h in g v i b r a t i o n , 5 - ben d in g v i b r a t i o n , s — s tr o n g , m — medium, w — weak, v — v e r y weak.
Jo an na M as ło w sk ą, L on gin C h ru śc iń sk i
/
T a b l e 4 S p e c t r a l d a ta o f t h e C r ( I I I ) complexes w it h DL-methionine
and L - c y s t e in e
Band 1 Band 2 Band 5 Bat... ;...
Complex max
X
lo g E
[mOl cm” '] maxX log £ maxX
lo g E A l o g fS C riD L - M e t)32H2Oa ,!aC r(L - C y s ) 22H20b 416 408 1,71 1 ,7 3 467 1,67 ->71 541 1,79 1,71 505 ! , 8 ‘i_ a Spectrum Ln 30rf HCIO^. ^ Spectrum i n H^O pH • 7 . 0 .
bond. S i m i l a r l y , t h e s h i f t o f s y m e t r i c and asym m etric s t r o ' : ' h i : ; - v i b r a t i o n s o f c a r b o x y l i c group from 1390 cm" 1 and 1400 c:a t o 1620 cm-1 and 1420 c m '1 , r e s p e c t i v e l y , p o i n t s t o t h e for:::.', t:Lon o f a Cr-0 bond. A ccord ing t o M c A u 1 i f i e [ 2 0 ] , t h e ■ d i f f e r e n c e A^CCOO“ ) between V(C00 ^3yn i anc* V(C00 S y.?J i- -1 measure o f t h e C r-0 bond s t r e n g t h (AV20Q c o n fir m s t h a t t i . ; bond i s a s t r o n g o n e ) .
S i n c e t h e r e i s no change i n t h e p o s i t i o n o f sym m etric and asym m etric s t r e t c h i n g v i b r a t i o n s o f t h e C-S bond, i t would e s t t h a t s u l p h u r i n t h e t i o e t h e r g roup i s n o t combined w i t h c h r o mium. The band3 i n s p e c tru m o f t h e complex ;Ja[ C r(C y s )2 ] . ' ■■ .,J were a l s o c l e a r l y changed a s compared w i t h th e c y s t e i n e -tru m . I n t h e complex s p e c tr u m , t h e r e i s no band c o rr e ;p o .v : ;., , ;.o s t r e t c h i n g v i b r a t i o n V(S - H), and th e band o f s t r e t c h i n g b r a t io n V(C - S) i s i n t h e complex a t 670 cr*~ ’ , wxucj. t h a t th e s u l p h h y d r i l e group can t a k e p a r t i n the-
w i t h m e t a l . The c h a r a c t e r i s t i c band f o r t h e s t r o t c r . i n - - i'>-i V(C - 0) 1740 cm" 1 i n t h e u n d i s s o c i a t e d c a rb o i:} ¿. i
•* "1
s h i f t e d i n t h e complex t o 1640 cm , which show t h a t _v. - x y l i c group t a k e s * p a r t i n t h e c o m b in a tio n v.‘. t u :. p o s s i b i l i t y o f such a l i n k i s s u p p o r t e d by t : ■
a l s o t y t h e f o r m a ti o n o f th e b en d in g v i b r a c io n S(NH2 ) a t 1560 cm"1 , which i s a c h a r a c t e r i s t i c f e a t u r e f o r th e c o n t r i b u t i o n o f n i t r o g e n o f ornine group in th e bond o f m e ta l io n [ 2 1 ) .
Tie e l e c t r o n i c spectrum o f t h e complex Na [ C r ( c y s ) 2 ] . 2H20 show 4 c h a r a c t e r i s t i c a b s o r p t i o n bands 467, 408, 541, 606 nm (Tab. 4 ) . Bands 467 and 541 no r e s u l t from th e d i v i s i o n o i bonds 408 and 606. Such a d i v i s i o n o f bands c h a r a c t e r i s t i c f o r C r ( I I I ) and C o ( I I I ) complexes w ith am in o acid s [22] w hich can form two g e o m e tric isom er3 mer ( c i s , t r a n a ) and f a c ( c i s , . c i s ) due t o th e p o s i t i o n o f bonds N -m etal and 0 - m e ta l. I t has been found [22] t h a t some s o r t o f d i v i s i o n in th e bands o f e l e c t r o n i c sp e ctru m t a k e s p l a c e im th e iso m er m e r ( c is , t r a n s ) w hich i s a complex o f v i o l e t c o lo u r and i s r e f e r r e d t o a s form oc . The isom er f a c ( c i s , c i s ) i s r e d i n c o lo u r and p r e s e n t s form (J. The C r ( I I I ) complex o b t a i n e d w i t h c y s t e i n e i s v i o l e t i n c o lo u r , be
in g an ocform . The e l e c t r o n i c spectru m o f t h i s com plex shows a d i v i s i o n o f t h e b a n d s . The s o l u t i o n o f t h e complex Na[Cr(Cys>2 ] 2^ 0 , i n an a c i d i c medium, changes i t s c o lo u r from v i o l e t to r e d and has o n l y two bands 394 and 529 nm i n i t s a b s o r p tio n sp e ctru m . The s p e ctru m o f th e complex s o l u t i o n f o llo w in g n e u t r a l i s a t i o n shows a l s o two bands 398 and 571 nm. T h is s o l u t i o n i s v i o l e t i n c o l o u r . The s p e c t r a l a n a l y s i s shows t h a t th e com plex N a[C r(C ys),,] 2H20 i n n e u t r a l and a l k a l i n e s o l u t i o n s assu m ies t h e form oc, bu t i n a c i d i c s o l u t i o n - t h e form f t. The t r a n s i t i o n p r o c e s s from oc t o <b form i s n o t a r e v e r s i b l e o n e .
The r e a c t i o n m ix t u r e , from which complex N a [C r(C y s)g ]. 2H20 was p r e p a r e d , was s e p a r a t e d i n a c h ro m a to g r a p h ic column f i l l e d w i t h an io n -e x c h a n g e r e s i n (Sep hadex A - 2 5 ) . By e l u t i o n w i t h 1-10» NaCl s o l u t i o n s , t h r e e f r a c t i o n s w ere s e p a r a te d : one o f r e d c o l o u r which was n o t i d e n t y f i e d , an d two o f b l u e c o l o u r . The f i r s t b lu e f r a c t i o n was i d e n t i e d a s [Cr(H20 ) ^ ] w h i l e t h e s e c o n d one had a s p e ctru m a n a lo g o u s t o t h a t o f Na[Cr(Cys>2] 21^0 in th e oc form.
R e f e re n c e s
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C16] K. J . B j e r r u m, Dan. V idensk. S e l s k . M a t.- F y s . Medd., 4 , 21 (1 9 4 4 ). [1 7 ] F. B a s o 1 o , Y. T. C 1 1 e n , J . Am. Chem. S o c . , 76 , 953 (1 9 5 4 ). [1 8] H. M a t s u k a w a , M. 0 k t a , B u ll. Che. S o c . J a p . , 3 8 , 1235 (1 9 6 5 ). [1 9 ] R. G. P e a r s o n , J . Chem. E d u c ., 5 , 45, 581, 643 (1 9 6 8 ). [2 0 ] C. A. M e A u 1 i f f e , W. 0 . P e r r y, J . Chem. Soc. A . , 634 ( 1 9 6 9 ). [21 ] A. S h i n d o , B. B r 0 w n , J . Am. Chera. S o e . , 7 8 , 1234 (1 9 5 6 ).
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CQ
[ 22] j \ l i i d a k a , Y. S h 1 in u r a , . R* T s u c h 1 d a , B u l i . Chem. S oc. J a p a n , 3 5 , 567 ( 1 9 6 2 ).
I n s t i t u t e o f Fundam ental Food C h em istry P o ly te c h n ic a l U n iv e r s ity
J oan na Masłowska, Longin C h r u ś c iń s k i KOMPLEKSY C r ( I I I ) Z DL-METIONINĄ I L-CYSTEINĄ
Kompleksy C r ( I I I ) z D L -m etioniną i L - c y s te in ą badano w r o z tw o rach wodnych metodami pH-m etryczną i a p e k tr o fo to m e try c z n ą . W obu badiinych u k ła d a c h s tw ie r d z o n o tw o rz e n ie s i e po 3 kompleksów o s k ł a d z i e C r ( I I I ) s L • 1 : 1; 1 s 2 ; o rą z 1 : 3 . Metodą B,jerruma o k r e ś l o n o w a r t o ś c i lic z b o w e s t a ł y c h t r w a ł o ś c i w sz y st k i c h tw o rzących s i ę kompleksów w r o z t w o r a c h . W s t a n i e k r y s t a l i t cznym otrzym ano kompleksy o s k ł a d z i e : [C r(M et)} ] 2HjO o ra z Wa[Cr(Cys)2] 2H2O. W o p a r c i u o wykonane widma IR zaproponowano budowy s t r u k t u r a l n ą otrzym anych p o ł ą c z e ń . Wykazano dużą p rz y d a tn o ś ć metody wymiany jonowej na żywicy Saphadex A-25 do wy d z i e l a n i a w s t a n i e czystym kompleksów chromu ( I I I ) z . tio a m in o - kwasami.
3aHHa MacjioBcica, JIoHraa XpycuHHtoKH K0M1TIEKCH C r ( I I I ) C DL-.METHOHUHOM H L-UUCTE^HOM
KOMrUieKCM C r ( I I I ) C DL-MeTHOHHHOM H L-UHCT6HH0 M HCCaeĄOBaHO d BO^Hax pOCTBOpax nOTeHUHOMBTpHqeCKMM H CneKTpOipOTOMeTpHMOCKHM
t e ' t o z . o i t . b HCCJienoBaHMx cncTeuax HacrynaeT 0 Gpa3 0 uaHHe komiijzex— o OB C r ( I I I ) - JwraHu, 1 s 1} 1 : 2j 1 : 3.
MeT o no m Bepywa onpe^ejieHO ko HCTaHTU yc?OKHHBOc?k Bcex KOMiute- <COB B pOCTBOpe. B KpHCTajIHHeCKOM (llŁie MU OlfcOpMHJIH KOMIJJieKCM: [C r(M et)3] 2H2O k N a[Cr(Cys)2] 2H20 . Ha 0CH0Be ojieMeHTapHoro / a - :ja-iH3a a cnex?po& IR m onpeAQJiw.t h x $opMyjty. Merono« aoHHoro »CneKa Ha CMOjte Sepadex A-25 mu 'pas^eJiiwH xoMnjieitcu C r ( I I I ) c T HOaMHHOKHCJIOTaMH.
