Scanning electrochemical microscopy assessment of rates of molecular transport through mesoporous thin-films of porphyrinic "Molecular squares"

被引:40
作者
Williams, ME
Hupp, JT
机构
[1] Northwestern Univ, Dept Chem, Evanston, IL 60208 USA
[2] Northwestern Univ, Ctr Nanofabricat & Mol Self Assembly, Evanston, IL 60208 USA
来源
JOURNAL OF PHYSICAL CHEMISTRY B | 2001年 / 105卷 / 37期
关键词
D O I
10.1021/jp010881b
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Scanning electrochemical microscopy (SECM), in combination with electrode platform micropatterning, has been used for qualitative characterization of molecular sieving and exceptionally precise quantitative measurement of molecular permeation through thin films of meso- and microporous materials composed of porphyrinic "molecular squares". SECM measurements reveal that modification of the squares, to reduce cavity sizes and alter the size cutoff for permeation, has only a modest effect upon the permeabilities of those probe molecules small enough to pass through the modified films. Additional experiments as a function of electrolyte composition show that the ability to observe sieving behavior electrochemically is determined not only by the relative sizes of redox-active permeant molecules and film-based cavity openings, but also by the steric properties of ions needed for charge compensation - even when the permeant molecule is initially neutral. As expected, when the size of the opening is altered the steric requirements for the charge-compensating ion are similarly altered. The experiments also show that charge-compensating ion transport can be convoluted to a small but measurable extent with the probe-molecule transport measurement. The identity of the component of the electrolyte not required for charge compensation, however, does not detectably affect the SECM-based permeation measurement.
引用
收藏
页码:8944 / 8950
页数:7
相关论文
共 32 条
[1]   Scanning electrochemical microscopy (SECM): An investigation of the effects of tip geometry on amperometric tip response [J].
Amphlett, JL ;
Denuault, G .
JOURNAL OF PHYSICAL CHEMISTRY B, 1998, 102 (49) :9946-9951
[2]  
Bard A.J., 1994, ELECTROANAL CHEM, V18, A., P243
[3]   SCANNING ELECTROCHEMICAL MICROSCOPY - INTRODUCTION AND PRINCIPLES [J].
BARD, AJ ;
FAN, FRF ;
KWAK, J ;
LEV, O .
ANALYTICAL CHEMISTRY, 1989, 61 (02) :132-138
[4]   DIGITAL-SIMULATION OF THE MEASURED ELECTROCHEMICAL RESPONSE OF REVERSIBLE REDOX COUPLES AT MICROELECTRODE ARRAYS - CONSEQUENCES ARISING FROM CLOSELY SPACED ULTRAMICROELECTRODES [J].
BARD, AJ ;
CRAYSTON, JA ;
KITTLESEN, GP ;
SHEA, TV ;
WRIGHTON, MS .
ANALYTICAL CHEMISTRY, 1986, 58 (11) :2321-2331
[5]   Scanning electrochemistry microscopy (SECM) in the study of electron transfer kinetics at liquid/liquid interfaces: Beyond the constant composition approximation [J].
Barker, AL ;
Unwin, PR ;
Amemiya, S ;
Zhou, JF ;
Bard, AJ .
JOURNAL OF PHYSICAL CHEMISTRY B, 1999, 103 (34) :7260-7269
[6]   Imaging molecular transport in porous membranes. Observation and analysis of electroosmotic flow in individual pores using the scanning electrochemical microscope [J].
Bath, BD ;
Lee, RD ;
White, HS ;
Scott, ER .
ANALYTICAL CHEMISTRY, 1998, 70 (06) :1047-1058
[7]   Thin-film molecular materials based on tetrametallic "squares":: Nanoscale porosity and size-selective guest transport characteristics [J].
Bélanger, S ;
Hupp, JT ;
Stern, CL ;
Slone, RV ;
Watson, DF ;
Carrell, TG .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1999, 121 (03) :557-563
[8]  
Bélanger S, 1999, LANGMUIR, V15, P837, DOI 10.1021/la980908r
[9]   Ion-gated electron transfer in self-assembled monolayer films [J].
Campbell, DJ ;
Herr, BR ;
Hulteen, JC ;
VanDuyne, RP ;
Mirkin, CA .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1996, 118 (42) :10211-10219
[10]  
CZAPLEWSKI K, UNPUB