1

Interface MD

Application

July 15, 2017

Hendrik HeinzDepartment of Chemical and Biological

EngineeringMaterials Science and Engineering Program

University of Colorado-Boulder, CO, USA

2

Predict Facet-Specific Binding of Peptides in

Solution to Surfaces and Nanoparticles (Pd)

Ramezani-Dakhel et al. 2017, 9, 8401-8409.

Pd4 @ {111} Pd4 @ {100}Pd4 @ {110}

10 Å

5 Pd4 @ 21 Å

5 Å

C D E

F G

∆𝑬𝒂 = -68±1 ∆𝑬𝒂 = +3±1∆𝑬𝒂 = -43±2

∆𝑬𝒂 = -20±1 ∆𝑬𝒂 = -17±1 Pd C N O H

7 Pd4 @ 26 Å 9 Pd4 @ 31 Å

∆𝑬𝒂 = -29±2

H

Pd4 peptide = TSNAVHPTLRHL

3

aPredict of Activity of Pd Nanoparticle Catalysts in C-C

Coupling Reactions (Stille Reaction)

H. Ramezani-Dakhel, M. R. Knecht, R. R. Naik, H. Heinz PCCP 2013; ACS Nano 2015, 9, 5082; Chem. Sci. 2015, 6, 6413.

Catalytic efficiency is predictable for any

given particle shape, determined from HE-

XRD/PDF data, and using the computed

atom leaching rate

Ei : abstraction energy of atom i

N

i

RT

E

N

i

eN

R1

1~

RN : total rate of abstraction

N : total number of surface atoms

a b

c

35-45

45-55

55-65

25-35

65-75

> 85

Abstraction energy

(kcal/mol)

75-85

Ei : abstraction energy of atom i

N

i

RT

E

N

i

eN

R1

1~

RN : total rate of abstraction

N : total number of surface atoms

a b

c

35-45

45-55

55-65

25-35

65-75

> 85

Abstraction energy

(kcal/mol)

75-85

Ei : abstraction energy of atom i

N

i

RT

E

N

i

eN

R1

1~

RN : total rate of abstraction

N : total number of surface atoms

a b

c

35-45

45-55

55-65

25-35

65-75

> 85

Abstraction energy

(kcal/mol)

75-85

Mechanism

Particle

shape

(Pd4)

Ei : abstraction energy of atom i

N

i

RT

E

N

i

eN

R1

1~

RN : total rate of abstraction

N : total number of surface atoms

a b

c

35-45

45-55

55-65

25-35

65-75

> 85

Abstraction energy

(kcal/mol)

75-85

Activity

Ei : abstraction energy of atom i

N

i

RT

E

N

i

eN

R1

1~

RN : total rate of abstraction

N : total number of surface atoms

a b

c

35-45

45-55

55-65

25-35

65-75

> 85

Abstraction energy

(kcal/mol)

75-85

Rate

determining

step

4

Explain Interlayer Structure in Clay Minerals

(Alkylammonium-Montmorillonite)

• Increase of basal-plane spacing in a step-like pattern according to the

formation of an alkyl monolayer, alkyl bilayer etc (<5% dev from XRD)

• Gallery spacing for peralkylated head groups rises smoothly and is shifted by

~ 2 C atoms relative to primary ammonium head groups (“bumpy” due to H bonds)

0 2 4 6 8 10 12 14 16 18 20 22 2412

13

14

15

16

17

18

19

20

21

22

23

Ba

sa

l p

lan

e s

pa

cin

g (

A)

Carbon atoms per chain

NH3 head group

NMe3 head group

monolayer

complete

bilayer

complete

HRTEM of MMT

embedded in an

epoxy matrix

(Drummy et al.

JPCB 2005)

Heinz et al. J. Am. Chem. Soc. 2003, 125, 9500. Heinz et al. Chem. Mater. 2007, 19, 59-68.

(CnH2n+1NR3)0.33(Si4O8)[Al1.67Mg0.33O4(OH)4]

CEC 90 mmol/100g

5

Identify Atomic Positions and Structure in Alloys

and Carbides By Imaging Plus Simulation

3D structure of a WCx tip containing

amorphous carbon inclusions:

x ~0.15 at surface and ~8 layers penetration

Str

ain

fie

ld in

exp

eri

me

nt

Str

ain

fie

ld in

MD

sim

ula

tio

n

With Jianwei Miao, UCLA,

U. Dahmen, LBL,

W. Ercius, Birmingham (UK)

Imaged at TEAM I

(currently largest EM)

Xu et al. Nat. Mater. 2015, 14, 1099.

6

Understand Mechanisms of Cement Hydration

(CSH) with Polycarboxylate Ethers

(100) surface of

tobermorite 14 Å

7

Supply Realistic, pH-Resolved Surface Models –

Example: Silica Surface Model Database

0% ionized – 4.7 OH/nm2 (pzc)

pH~4 for 20 nm particle

pH~2.5 for 400 nm particle*

9% ionized –

pH~7 for 20 nm particle

pH~5 for 400 nm particle

18% ionized –

pH~9 for 20 nm particle

pH~7 for 400 nm particle

Typical: Q3 surfaces, 4.7 SiO(H,Na) per nm2, with 0-20% ionization

Amorphous Q3, Q3/Q4, Q2 surfaces with 0-20% ionization

Si O O- Na+ H

2 nm

Emami, Perry, and Heinz et al. Chem. Mater. 2014, 26, 2647.

8

Understand Nanocrystal Growth – Example:

Hydroxyapatite Biomineralization

Exptl data from C. Tamerler, U Kansas

(020)

-27-25

-15

-48

HAp (001) HAp (101) HAp (010) HAp (020)0

-10

-20

-30

-40

-50

Ad

so

rpti

on

en

erg

y (

kc

al/

mo

l)

HAp cleaved surface

Peptide HABP 1 strong binding

(MLPHHGA)

11

-15

5

14

HAp (001) HAp (101) HAp (010) HAp (020)20

15

10

5

0

-5

-10

-15

-20

Ad

so

rpti

on

en

erg

y (

kc

al/

mo

l)

HAp cleaved surface

Peptide HABP 2 nonbinding

(NPGFAQA)

(020)

(020)

9

Explain Molecular Control Over Pt Nanocrystal Shape

Using a Phenyl Molecular Switch

Y. Huang and H. Heinz et al. Nano Letters 2013, 13, 840.

Synthesis

from H2PtCl6with sodium

borohydride

and ascorbic

acid in the

presence of

peptides

Binding

contrast

between

{111} and

{100}

surfaces

determines

preferred

shape

With Y. Huang,

UCLA

Ramezani-Dakhel et al. Adv. Funct. Mater. 2015, 25, 1374.

10

• Up to 70% reduction in cohesive

energy of hydroxylated (040)

cleavage plane by grinding aids

• Significant differences among

molecules depending on surface-

specific mitigation of local electric

fields0

100

200

300

400

500 HC: Hydroxylated C3S

Ag

glo

me

ratio

n E

nerg

y,

mJ/m

2

C3S HC HC-Gly HC-TEA HC-TIPA HC-MDIPA

Discover Mechanism of Mineral Agglomeration and

Working Principle of Grinding Aids (Ca3SiO5)

Mishra, Flatt, Heinz J. Phys. Chem. C 2013, 117, 10417. Sandmeyer Award (SCS 2016).

• 0.5 nm thin

organic layer

eliminates >90%

of attractive

Coulomb forces

Heinz, Farmer et al. J. Chem. Phys. 2006, 124, 224713.