Ca(Ⅱ)、Mg(Ⅱ)和Zn(Ⅱ)与丙二醇-水混合体系中L-多巴的二元配合物的生成平衡.pdf

第 2 9卷第 6期 2 0 1 3年 6月 无 机 化 学 学 报 C HI NE S E J 0 URNAL OF I NO RG ANI C C HEMI S T R Y Vo 1 2 9 No 6 1 2 35 1 24 2 C a 1 Mg 和 Z n 1 1 与丙二醇一 水混合体 系中 多巴的二元配合物的生成平衡 S a n t h e e D e v i K V R a ma r a j u B N a g e s w a r a R a o G D e p a r t m e n t o f I n o r g a n ic A n a ly t ica l C h e mis t r y A n d h r a U n iv e r s it y 安得拉大学无机和分析化 学系 V is a k h a p a t n a m 5 3 0 0 0 3 I n d ia 印度 摘要 在 3 0 3 K恒温条件下 以 N a C 1 为 电解质保持离子强度 为 0 1 6 to o l L 用 p H滴定 法研究 了 M I I 一 D o p a 巴 二元配合物 在 一 6 0 的丙二醇 P G 一 水体 系中的生成平衡 在 P G 水体系 中 c a 和 M 的典型配合 物为 ML H MI J 2 ML t t 和 ML 2 H 而 z n 的典型配合物为 ML ML H ML M L z H和 M L 2 H 根据静 电和非静 电力 解释了稳定常数 随介 质的介电常数而变化 的倾 向 还讨论 了在不同组成的丙二 醇 P G 一 水体系 中配合物物种 随 p H值变化的情况 关键词 二元物种 金属 配体 丙二醇 p H滴定 中图分类号 0 6 1 4 4 文献标识码 A 文章编号 1 0 0 1 4 8 6 1 2 0 1 3 0 6 1 2 3 5 0 8 DOI 1 0 3 9 6 9 i s s n 1 0 0 1 4 8 6 1 2 0 1 3 O 0 1 8 0 B i n a r y C o mp l e x F o r ma t io n E q u il i b r i a o f C a I I wit h L do p a in Pr o p y le ne Gly co l W a t e r Mg 1 I a n d Z n II M ix t ur e s S a n t h e e D e v i K V R a m a r a j u B N a g e s w a r a R a o G D e p a r t m e n t o f I n o r g a n ic A n a l y t ica l C h e m is t r y A n d h r a U n iv e r s i t y V i s a k h a p a t n a m 一 5 3 0 0 0 3 I n d i a Ab s t r a ct T h e co m p le x f o r m a t io n e q u i li b r ia in v o lv e d in t h e b in a r y s y s t e m s o f M Do p a in 0 6 0 f V V p r o p y le n e g ly co l P G w a t e r m ix t u r e s w e r e s t u d ie d u s in g p H me t r ic t it r a t io n a t co n s t a n t t e m p e r a t u r e o f 3 0 3 K a n d a co n s t a n t io n ic s t r e n g t h o f 0 1 6 mo l L h e ld b y u s in g s o d iu m ch lo r id e a s a n e le ct r o ly t e T h e mo d e ls co n t a in e d ML H ML 2 ML 2 H a n d M H 2 f 0 r C a a n d Mg n b u t ML ML H ML 2 ML 2 H a n d ML 2 H 2 f 0 r Z n 1 I in P G w a t e r mi x t u r e s T h e t r e n d in t h e v a r i a t io n o f s t a b ilit y co n s t a n t s w it h ch a n g e in t h e d ie le ct r ic co n s t a n t o f t h e me d iu m wa s e x p la in e d o n t he b a s is o f e le ct r o s t a t ic a n d n o n e le ct r o s t a t ic f o r ce s Dis t r ib u t io n s o f t h e s e s pe cie s wit h pH v a lu e a t d iff e r e n t co mp o s it io n s o f P G wa t e r mi x t u r e s w e r e a lS O p r e s e n t e d Ke y wo r ds bin a r y s p e cie s me t a l lig a nd pr o p y le n e g lycol pH me t r ic me t h o d 0 I nt r o du c t io n I n r e ce n t y e a r s co n s id e r a b le a t t e n t i o n h a s b e e n pa id f o r t h e in v e s t i g a t i o n o f t he co mple x f o r min g p r o p e r t ie s o f lig a n d s w it h me t a l io n s f o r t h e ir o u t s t a n di ng b io lo g ica l s ig n if ica n ce I n bio lo g i ca l fl u id s me t a l io n s e x is t i n n o n e x ch a n g e a b le f o r ms a s in me t a llo p r o t e in s o r lo o s e ly b o u n d t o s o me b io lo g ica l lig a n d s a s in me t a l a ct iv a t e d p r o t e ins Th e lo o s e ly b o u n d me t a l io n s a r e i n e q u ilib r iu m wit h s i mil a r me t a l io n s p r e s e n t i n t h e b io fl u id s T he s e s imu lt a n e o us e q u ilib r ia in v o lv in g a v e r ie t y o f me t a l io n s a n d lig a n d s a r e imp o r t a n t in b io lo g ica l fl u id s l 5 1 Me t a l io n s a r e ca pa ble o f co o r di na t in g wit h 收稿 日 J D a t e R e ce i v e d 2 0 1 3 0 1 0 1 收修改稿 日g q D a t e R e v i s e d 2 0 1 3 0 3 0 2 C o r r e s p o n d in g a u t h 0 r f 通讯联系人1 E ma ih g o l l a p a l l in r y a h o o co m 1 2 3 6 无机化学学报 第 2 9卷 a min o a n d ca r b o x y la t e g r o u p o r w it h p y r o e a t e ch o l p h e n o lic h y d r o x y l g r o u p s o f d o p a a t p h y s io lo g ica l p H v a lu e Do p a is a n a t u r a lly o ccu r r in g d ie t a r y s u p p le me n t a n d p s y ch o a ct i v e d r u g f 0 u n d in ce r t a in k in d s o f f o o d a n d h e r b s I t s r ich e s t n a t u r a l s o u r ce is f r o m p la n t k in g d o m i e t h e s e e d o f mu cu n a p r u r ie n s 1 0 1 I t is s y n t h e s is e d f r o m t h e e s s e n t ia l a min o a cid L p h e n y la la n i n e a n d L t y r o s in e in t h e ma mma lia n b o d y a n d b r a in As id e fro m it s na t u r a l a nd e s s e nt ia l b io lo g ica l r o le d o p a is a p o p u la r d rug in t h e t r e a t me n t o f ma ng a n e s e p o is o n in g a nd Pa r k in s o n s dis e a s e 1 M2 wh ich a r e a cco mp a n ie d b y n e u r o lo g ica l ly s o me w h a t s imil a r s e q u e ls f 1 3 P r o p y le n e g ly co l P G a ls o k n o w n a s p r o p y le n e g ly co l is p r o d u ce d b y f e r me n t a t io n o f y e a s t a n d ca r b o h y d r a t e s I t is me t a b o liz e d in t h e h u ma n b o d y in t o p y ru v i c a cid which is a n o r ma l p a r t o f t he g lu co s e me t a b o lis m p r o ce s s a n d i s r e a d i ly co n v e r t e d in t o e n e r g y I t is u s e d a s a s o lv e n t a s i t is s o lu b le in b o t h wa t e r a n d o r g a n ic ma t e r ia ls T h e o r a l t o x icit y o f p r o p y le n e g ly co l is v e ry l o w a nd la r g e q u a n t it ie s a r e r e q u ir e d t o ca u s e p e r ce p t ib le h e a lt h d a ma g e in h u ma n s S e r i o u s t o x icit y w ill o ccu r o n ly a t p la s ma co n ce n t r a t io ns o v e r 4 g L wh ich r e q ui r e s e x t r e me ly h ig h i n t a k e o v e r a r e la t iv e ly s h o r t p e ri o d o f t ime I t wo u ld b e n e a r ly i mp o s s ib le t o r e a ch t o x ic le v e ls b y co n s u min g f o o d s o r s u p p le me n t s w h i ch co n t a in a t mo s t 1 g k g 一 o f PG 1 5 C a lci u m is t h e mo s t a b u n d a n t min e r a l f o u n d i n t h e h u ma n b o d y C a lciu m d e fi cie n cy f o r a lo n g p e r io d le a d s t o o s t e o p o r o s is lo s s o f t h e j a w b o n e o s t e o n e e r o s is h y p e r t e n s io n a n d o t h e r d is o r d e r s t Ma g n e s iu m is in v o lv in g i n mo r e t h a n 3 0 0 me t a b o lic r e a ct io n s a n d a ls o h e lp s t o r e g u la t e b lo o d s u g a r le v e ls p r o mo t e s n o r ma l b lo o d p le a s u r e a n d is k n o wn t o b e in v o lv e d in e n e r g y me t a b o lis m a n d p r o t e in s y n t h e s is 捧 Z in c is r e qu ir e d f o r a la r g e nu mb e r o f p h y s icd o g i ca l a n d b io ch e mica l f u n ct io n s 排2 7 l a n d it p la y s e it h e r a p r e d o min a n t l y ca t a ly t i c r o le o r s o le ly s t r u ct ur a l r o le t o ma i nt a in t h e p r o t e in co n f ig ur a t i o n 2 s 1 He n ce s p e cia t io n s t u d ie s for co mp le x e s o f d o p a ha v e b e e n un d e rta k e n in t his la b o r a t o r y Pr o t o n a t io n co ns t a nt s o f d o p a n Dio x a n wa t e r a nd PG wa t e r p mi x t u r e s h a v e b e e n r e p o rte d B in a r y co mp le x e s o f t h e t it le s y s t e ms h a v e b e e n u n d e rt a k e n b a s e d o n t h e ir in v o lv e me n t in v a ri o us p h y s io lo g i ca l r e a ct io n s 1 Ex pe r im e n t a l 1 1 M at e r ia ls a nd m e t h o ds 0 0 5 m o 1 L s o lu t i o n o f L D o p a f L o b a I n d ia wa s p r e p a r e d in t r ip le d is t ille d d e io n iz e d wa t e r b y ma i nt a in ing 0 05 too l L h y d r o ch lo r ic a ci d co ne e n t r a t io n t o i n cr e a s e t h e s o lu b ilit y 1 2 P r o p y lin e g ly co l F in a r I n d ia w a s u s e d a s r e ce iv e d H y d r o ch lo r ic a cid Q u a lig e n s I n d i a o f 0 2 m o l L w a s p r e p a r e d S o d i u m ch lo r id e Q u a lig e n s I n d ia o f 2 m o l L w a s p r e p a r e d t o ma in t a i n t h e i o n ic s t r e n g t h in t h e t it r a n d S o lu t io n s o f C a Mg 1 I a n d Z n I I ch lo r id e s f 0 0 5 m o l L 1 w e r e p r e p a r e d b y d is s o lv in g G R G r a d e Me r ck I n d ia s a lt s in t r ip ly d is t ille d w a t e r m a in t a in i n g 0 0 5 m o l d m a cid HC 1 t o s u p p r e s s t h e h y d r o ly s is o f m e t a l s a l t s S o d iu m h y d r o x id e Q u a lig e n s I n d ia o f 0 4 mo l L wa s p r e p a r e d All t h e s o lu t io n s we r e s t a n d a r d i z e d b y s t a n d a r d me t h o d s T o a s s e s s t h e e r r o r s t h a t mi g h t h a v e cr e p t in t o t h e d e t e r min a t io n o f t h e co n ce n t r a t io n s t h e d a t a w e r e s u b j e ct e d t o a n a l y s is o f v a r i a n ce o f o n e w a y cla s s ifica t io n f A N O V A 3 l J T h e s t r e n gth s o f a lk a li a n d min e r a l a cid w e r e d e t e r min e d u s in g t h e Gr a n p lo t me t h o d 3 2 3 1 2 Pr oce du r e Th e t it r i me t r ic d a t a we r e o b t a in e d u s in g ca li br a t e d E L I C O Mo d e l L I 一 1 2 0 p H m e t e r r e a d a b ilit y O O 1 T h e g la s s e le ct r o d e wa s e q u ilib r a t e d in a we ll s t ir r e d P G w a t e r mi x t u r e s 0 6 0 V V co n t a in in g i n e r t e le ct r o ly t e for s e v e r a l d a y s T h e e f f e ct s o f v a r ia t io n s i n a s y m m e t ry liq u id j u n ct io n p o t e n t ia l a ct iv it y co e ff i cie n t s o d i u m io n e r r o r a n d d is s o l v e d ca r b o n d i o x id e o n t h e r e s p o n s e o f g la s s e le ct r o d e we r e a cco u n t e d for in t h e f o rm o f co r r e ct io n f a ct o r 3 4 1 F o r t h e d e t e r min a t io n o f s t a b ilit y co n s t a nt s o f bin a ry s p e cie s in it ia lly t it r a t e d s t r o n g a cid wit h a lk a li a t r e g u la r in t e r v a ls t o ch e ck t h e co mp le t e e q u i lib r a t i o n o f t h e g la s s e le ct r o d e T h e n t h e e a lo me l e le ct r o d e w a s r e fi lle d wit h P G w a t e r mi x t u r e o f t h e s a me co mp o s it i o n a s t h a t o f t h e t it r a n d All t h e t i t r a t io n s w e r e p e rf o r me d in me d iu m co n t a in in g v a r y in g co n ce n t r a t io n s o f PG w a t e r 第 6期 S a n t h e e D e v i K V等 C a 1 I M g I I z n j 与丙二醇一 水混合体系中 多 巴的二元配合物 的生成平衡 1 2 3 7 mix t u r e s 0 6 0 V V p H m e t r ica lly a t 3 0 3 0 1 K I n e a ch o f t h e t it r a t io n s t h e t it r a n d co n s is t e d o f a p p r o x ima t e ly 1 mmo l min e r a l a ci d in a t o t a l v o lu me o f 5 0 e m Tit r a t io n s wit h d if f e r e nt r a t io s f 1 2 5 1 3 7 5 a n d 1 5 1 o f me t a l t o lig a nd we r e ca r r ie d wit h 0 4 mo l L一 s o di um h y dr o x id e 1 3 M o de ling s t r a t e g y T he co mp u t e r pr o g r a m SCPHD wa s us e d t o ca lcu la t e t h e co r r e ct io n f a ct o r By u s in g p H me t r ic t it r a t i o n d a t a t h e b in a r y s t a b ilit y co n s t a n t s we r e ca lcu la t e d w it h t h e co m p u t e r p r o g r a m MI N I Q U A D 7 5 wh ich t a k e s t h e a d v a n t a g e o f co n s t r a in e d le a s t s q u a r e s me t ho d in t h e in it ia l r e fi n e me n t a nd r e lia ble co n v e r g e n ce o f Ma r q u a r d t a lg o r it h m Du r in g t h e r e fi n e me n t o f b in a r y s y s t e ms t h e co r r e ct io n f a ct o r a n d p r o t o n a t io n co ns t a n t s o f d o p a we r e fi x e d Th e v a r ia t io n o f s t a b ilit y co ns t a n t s wit h t he d ie le ct r ic co n s t a nt o f t h e me d iu m wa s a n a ly z e d o n t h e b a s is o f e le ct r o s t a t ic n o n e le ct r o s t a t ic s o lu t e s o lu t e a n d s o lu t e s o lv e n t in t e r a ct io n s 2 Re s ult s a n d d is cus s io n lI h e r e s u lt s o f t h e be s t fi t mo d e ls t ha t co n t a in t he s t o ichi o me t r y o f t h e co mp le x s p e ci e s a n d t h e ir o v e r a ll f o r ma t i o n co ns t a n t s a l o n g wit h s o me o f t h e impo r t a n t s t a t is t i ca l p a r a me t e r s a r e g i v e n i n T a b le 1 Ve ry lo w s t a n d a r d d e v ia t i o n in o v e r a ll s t a b ilit y co n s t a n t s 1 g s ig n ifi e s t he p r e cis io n o f t h e s e co ns t a n t s Th e s ma ll v a lu e s o f U s u m o f s q u a r e s o f d e v ia t io n s in co nce n t r a t io n s o f li g a n d a n d h y dr o g e n io n a t a ll e x p e r im e n t a l p o in t s co rr e ct e d f o r d e g r e e s o f f r e e d o m s ma ll v a lue s o f me a n s t a n da r d d e v ia t i o n a n d me a n d e v ia t i o n for t h e s y s t e ms a r e v a lid a t e d b y t h e r e s id u a l a n a ly s is 2 9 1 T a b l e l P a r a me t e r s o f b e s t fit ch e mica l mo d e l s o f C a Mg H a n d Z n 1 I d o p a co mp le x e s i n P G w a t e r mi x t u r e s U U N P m x l0 N P Nu m b e r o f p o i n t s m n u m b e r o f s t a b i li t y co n s t a n t s S D S t a n d a r d d e v i a t i o n 1 2 3 8 无机化学学报 第 2 9卷 2 1 Re s id ua l a n aly s is I n d a t a a na ly s i s wi t h le a s t s q u a r e s me t h o ds t h e r e s id u a ls t h e d if f e r e n ce s b e t w e e n t h e e x p e r im e n t a l da t a a n d t he d a t a s imu la t e d b a s e d o n mo d e l p a r a me t e r s a r e a s s u me d t o f o l lo w G a u s s ia n d is t r ib u t io n Wh e n t h e d a t a a r e fi t in t o t h e mo d e ls t h e r e s i d u a ls s h o u ld i d e a lly b e e q u a l t o z e r o I f s t a t is t ica l me a s u r e s o f t h e r e s id u al s a n d t he e r r o r s a s s ume d in t h e mo d e ls a r e n o t s i g n ifi ca n t ly d i f f e r e n t f r o m e a ch o t h e r t h e mo d e l is s a id t o b e a d e q u a t e F u r t h e r a mo d e l is co n s id e r e d a d e q u a t e o n ly if t h e r e s id u a ls d o n o t s h o w a n y t r e n d Re s p e ct in g t he hy po t he s is t ha t t he e r r o r s a r e r a n d o m f o llo win g n o r ma l d is t r i b u t io n in t h e le a s t s q u a r e s a n a ly s is t he r e s id u a ls a r e t e s t e d f o r n o r ma l d is t r ib u t i o n S u ch t e s t s a r e s k e w n e s s k u r t o s is a n d R f a ct o r T h e s e s t a t is t ica l p a r a me t e r s s h o w t h a t t h e b e s t fi t mo d e ls p o r t r a y t h e me t a l lig a n d s p e cie s in P G wa t e r mi x t u r e s a s d is cu s s e d b e lo w 2 1 1 t e s t is a s p e cia l ca s e o f g a mma dis t r ib u t io n who s e pr o b a b ilit y de ns it y f u n ct io n is a n a s y mme t ri ca l f u n ct i o n T h is d is t r i b u t io n me a s u r e s t h e p r o b a b ilit y o f r e s id u a ls f o r min g a p a rt o f s t a n d a r d n o r ma l d is t r ib u t io n wi t h z e r o me a n a n d u n it s t a n d a r d d e v ia t io n I f t h e ca lcu la t e d is le s s t h a n t h e t a b le v a lu e t h e mo d e l is a cce p t e d 2 1 2 Cr y s t a llo g r a p h ic R t e s t Ha mih o n s R f a ct o r r a t i o t e s t is a p p lie d in co mp le x e q u ilib r ia t o d e cid e wh e t h e r in clu s io n o f mo r e s pe cie s i n t h e mo d e l is n e ce s s a ry o r n o t I n p H me t r ic me t h o d t h e r e a d a b ilit y o f p H me t e r i s t a k e n a s t h e t wh ich r e pr e s e n t s t h e u p p e r b o u n d a ry o f R b e y o n d wh i ch t h e mo d e l b e a r s n o s i g n ifi ca n ce W h e n t h e s e a r e d if f e r e n t n u mb e r s o f s p e cie s t h e mo d e ls wh o s e R v a lu e s a r e g r e a t e r t h a n t a b le v a lu e s a r e r e j e ct e d T h e lo w cr y s t a llo g r a p h ic R v a lu e s g iv e n in T a b le 1 in d ica t e t h e s u fficie n cy o f t h e mo d e 1 2 1 3 S k e wne s s I t is a d ime n s io n le s s q u a n t it y in d ica t in g t h e s h a p e o f t h e e r r o r d is t r ib u t io n p r o fi le A v a lu e o f z e r o for s k e wn e s s i n d ica t e s t h a t t h e u n d e r l y in g d is t r ib u t io n is s y mme t r i ca 1 I f t h e s k e wn e s s is g r e a t e r t h a n z e r o a n d t h e p e a k o f t h e e r r o r d is t r ib u t io n cu r v e is t o t h e le f t o f t h e me a n a nd if t h e s k e wn e s s is le s s t h a n z e r o t h e p e a k is t o t h e r ig h t o f t h e me a n Th e v a lu e s o f s k e wne s s r e co r d e d in Ta b le 1 a r e b e t we e n 一1 49 a n d 0 4 2 for C a I 一 0 7 3 a n d 1 0 6 fo r Mg I I a n d一 1 2 6 a n d 0 3 2 fo r Z n 1 1 T h e s e d a t a e v in ce t h a t t h e r e s i d u al s for m a p a rt o f n o r ma l d is t r ib u t i o n h e n ce le a s t s q u a r e s me t h o d ca n b e a p p lie d t o t h e pr e s e n t d a t a 2 1 4 Ku r t o s is I t is a me a s u r e o f t h e p e a k e d n e s s o f t h e e r r o r d is t ri b u t io n n e a r a mo d e l v a lue F o r a n i de a l no rm a l d is t r ib ut io n k ur t o s is v a lu e s h o u ld b e t h r e e me s o k u r t ic I f t h e ca lcu la t e d k u rt o s is is le s s t h a n t h r e e t h e p e a k o f t h e e r r o r d is t r ib ut i o n cu r v e i s fl a t p la t y k u r t ic a n d i f t h e k u r t o s is is g r e a t e r t h a n t h r e e t h e d is t r ib u t io n s h a ll h a v e s h a r p p e a k 1 e p t o k u rt ie 2 2 Effe ct o f s y s t e m a t ic e r r or s o n be s t fi t m o de l I n o r d e r t o r e ly u p o n t h e b e s t ch e mica l mo d e l for cr it ica l e v a lu a t io n a n d a p p lica t io n u n d e r v a r ie d e x p e ri me n t a l co n d i t i o n s wi t h d if f e r e n t a ccu r a cie s o f d a t a a cq u is it i o n a n in v e s t i g a t i o n wa s ma d e b y in t r o d u 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