Nickel-catalyzed: Syn -stereocontrolled ring-opening of oxa- and azabicyclic alkenes with dialkylzinc reagents

Article abstract of DOI:10.1039/c8ob02864h

A new nickel-catalyzed syn-stereocontrolled ring-opening of oxa- and azabicyclic alkenes with dialkylzinc reagents was developed, which afforded the corresponding cis-2-alkyl-1,2-dihydronaphthalen-1-ols and 1,2-alkyl amide derivatives in moderate to excellent yields (up to 99% yield) under mild conditions. In this work, we successfully avoided obtaining hydride addition byproducts arising from β-hydride elimination on an ethyl nickel species. Furthermore, a plausible mechanism for the ring-opening reaction was also proposed.

Full text of DOI:10.1039/c8ob02864h

Surface & Coatings Technology 358 (2019) 611–616
Contents lists available at ScienceDirect
Surface & Coatings Technology
journal homepage: www.elsevier.com/locate/surfcoat
Formation of a carbonaceous film on the surface of Cu in a bovine serum
albumin solution
⁎
Q.Y. Deng, Y.L. Gong, P.P. Jing, D.L. Ma, Y.T. Li, T.T. Ye, N. Huang, Y.X. Leng
Key Laboratory for Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu,
Sichuan 610031, China
A R T I C L E I N F O
A B S T R A C T
Keywords:
Cu ion
Co ion
Protein
Tribo-layer
Carbonaceous film
Metal-on-metal (MOM) artificial joint
The tribochemical reaction between metal ions and proteins can result in the formation of a carbonaceous tribo-
layer on the surface of metal-on-metal (MOM) artificial joints. This carbonaceous film can lubricate the tribo-pair
and reduce the corrosion of the metal. The purpose of this work is to investigate the catalysis efficiency of Cu and
Co ions in the formation of carbonaceous films at the contact regions. A ball-on-disc (Al
Co alloy) friction mode in bovine serum albumin (BSA) solution was chosen for the wear test experiments. After
the wear test, the tribo-layer formed on the wear spot (on Al ball) and wear track (metal disc) were collected
2 3 2 3
O -on-Cu and Al O -on-
2 3
O
and characterized. The results show that the Cu ions released upon friction promoted the adsorption of BSA on
the wear track of Cu to give a protein film which was further transformed into a carbonaceous tribo-layer under
the shear force between the Al O -Cu tribo-pair. When the Al O ball and Co alloy were chosen as the tribo-pair,
2 3 2 3
however, a carbonaceous tribo-layer was not observed on the Co alloy after the wear testing. This means that the
catalysis efficiency of the Cu ion for the formation of a carbonaceous tribo-layer is stronger than that of the Co
ion.
1. Introduction
layer into the carbonaceous layer will occur over a long time in the
body. Therefore, finding a metal ion with a high catalysis efficiency to
Total hip arthroplasty (THA) is one of the most successful treat-
ments for hip joint disease in the United States [1,2]. Metal-on-metal
MOM) bearing have been widely employed in THAs over the past
transform the protein layer into a carbonaceous film will be a sig-
nificant advancement for the continued use of MOM artificial joints.
Erdemir et al. [13] reported that carbonaceous film can be formed on
the surface of friction interface by synergism of the catalytic abilities of
Cu and the shear force between the MoN-Cu film coated tribo-pairs,
when the pure poly-alpha-olefin (PAO) 10 oil was applied as the friction
medium. The aim of this work is to compare the catalysis efficiency of
Cu and Co ions for the formation of a carbonaceous film during friction
in the presence of a protein (bovine serum albumin, BSA) solution. A
ball-on-disc tribometer comprising of an alumina ball (Φ 6 mm) and
select Cu and Co alloy metal discs (Φ 10 mm × 1.5 mm) was used to
simulate the friction environment.
(
decade due to their toughness and good anti-wear properties [2–4]. For
example, in 2007 America, approximately 31% of primary THA im-
plants were MOM [1]. At present, however, MOM hip replacements are
not recommended since many reports reveal that the release of heavy
2
+
3+
metal ions (Co , Cr , etc.) and metallic debris [5–8] from MOM re-
sult in patient complications such as allergies and pseudotumor [9,10].
Martin et al. [11] discovered that the release of metal ions from
CoCrMo can promote the adsorption of protein onto the surface of the
substrate to form a protein layer. Liao et al. [12] inferred that this
protein layer can transform into a carbonaceous layer – via interactions
2
+
3+
between the transition metal ions (probably Co , Cr ) and the pro-
tein – with the potential to reduce the friction and improve the corro-
sion resistance of MOM implants. Such a carbonaceous layer was re-
ported by Liao et al. [12] on the surface of MOM prostheses retrieved
from patients.
2. Experimental
2.1. Materials and wear tests
The CoCrMo alloy (Co alloy, elastic modulus 177 ( ± 2) GPa, mi-
crohardness 568 ( ± 8) HV0.01) and copper (Cu, 99.9%, elastic modulus
What needs to be pointed out is that, for the more commonly used
CoCrMo alloy MOM bearings, the transformation process of the protein
102 ( ± 1) GPa, microhardness 135 ( ± 1) HV0.01
) discs, with
⁎
Corresponding author.
E-mail address: yxleng@263.net (Y.X. Leng).
https://doi.org/10.1016/j.surfcoat.2018.11.095
Received 3 October 2018; Received in revised form 26 November 2018; Accepted 29 November 2018
Available online 29 November 2018
0257-8972/ © 2018 Elsevier B.V. All rights reserved.

Q.Y. Deng et al.
Surface & Coatings Technology 358 (2019) 611–616
profiles of the wear tracks on the Cu and Co alloy discs are presented in
Fig. 2e. As shown, the depth of the wear track on the Cu disc is smaller
than that formed on the surface of Co alloy disc. This indicates that the
wear resistance of the Cu disc in the presence of the BSA solution is
better than that of Co alloy in the BSA solution. We infer that the “tribo-
layer” observed in the wear track of the Cu disc may have an important
influence on the wear resistance of Cu.
3.2. Raman and ATR-FTIR spectra of tribo-layer
In order to investigate the structure of the tribo-layers formed on the
wear tracks, micro-Raman spectra were acquired of the wear track
contact regions of the Al -Cu and Al -Co alloy tribo-pairs. The
Fig. 1. Schematic view of the tribology experiment.
2
O
3
2 3
O
results are shown in Fig. 3a and b. The Raman spectrum of the tribo-
layer formed inside wear track of the Cu disc (black area in Fig. 2a,
denoted with a yellow circle) showed strong Raman activity with a D
dimensions Φ 10 mm × 1.5 mm, were polished to a surface roughness
) of ~10 nm. After polishing, the discs were ultrasonically cleaned in
acetone and then in alcohol for 10 min each before being subjected to
wear testing.
Wear tests were performed using a ball-on-disc reciprocating trib-
ometer (CSEM, Switzerland) under a load of 1 N for 100,000 cycles.
2 3
Al O balls of 6 mm diameter were used to create the friction pairs
against the Co alloy and Cu discs in a total volume of 50 mL bovine
serum albumin solution (BSA solution, composition: BSA 20 mg/mL,
NaCl: 9 mg/mL, EDTA: 2 mg/mL, sorbic acid: 0.2 mg/mL) at a room
temperature of around 25 °C. The length of the wear track was about
(R
q
−1
−1
peak around 1380 cm
and a G peak around 1580 cm
(shown in
Fig. 3a). This indicated that the structure of the tribo-layer formed in-
side wear track of the Cu disc was comprised of graphite-like materials;
i.e., that it was a carbonaceous film. On the other hand, the Raman
spectrum of the wear track on the Co alloy (area in Fig. 2b, denoted
with a yellow circle) showed no Raman activity, similar to that of the
dried BSA (shown in Fig. 3b). That indicated that, under the conditions
employed in this work, the friction between alumina and the Co alloy
did not transform the BSA molecules in the wear track into a carbo-
naceous film.
6
mm and the sliding frequency was 1 Hz. The schematic view of the
tribology experiment setup is shown in Fig. 1.
In order to identify changes in the bonding of the BSA molecules
during friction, the Infra-Red spectra of the tribo-layers formed inside
wear tracks of the Cu and Co alloy discs were collected using
Attenuated Total Reflection Fourier Transform Infra-Red (ATR-FTIR)
spectroscopy. Dried BSA used as a control. The results, presented in
Fig. 3c and d, show that dried BSA contained two main peaks: the
2.2. Characterization of BSA adsorption
The adsorption of fluorescein isothiocyanate (FITC) modified BSA
molecules onto the wear track was determined from fluorescein images
captured using a Fluoresce Microscope (IX51, Olympus, Japan).
−
1
−1
amide I band at 1645 cm and the amide II band at 1530 cm . Fig. 3c
shows that the spectrum of outside wear track on the Cu disk is similar
to that of the dried BSA. The spectrum of the tribo-film formed inside
wear track on the Cu disk, however, was obviously different from that
2.3. Morphology of the wear track
−
1
of the dried BSA. A new absorption peak appears at 1600 cm , which
represents the formation of a eC]Ce bond (shown in Fig. 3c). This
clearly indicates that the structure of tribo-layer inside wear track on
the Cu disk was different to that of dried BSA, likely due to the dena-
turing of the BSA molecules under the cyclical shear force between the
alumina ball and the Cu disk to form the carbonaceous film. The
spectrum of tribo-layer formed inside wear track on the Co alloy (shown
After the wear tests, the morphology of wear tracks and spots were
investigated using an optical microscope (AX10, ZEISS, Germany). The
profile of the wear tracks was determined using a profilometer (XP2,
AMBIOS, USA).
2
.4. Characterization of the structure of tribological layer
−1
in Fig. 3d) showed a mere blue-shift of the amide I (from 1645 cm to
A Raman microscope (λ = 532 nm, InVia Raman Microscope,
−1
−1
−1
1
657 cm ) and amide II (from 1530 cm to 1546 cm ) bands. This
RENISHAW, Britain) and an Attenuated Total Reflection Fourier
Transform Infra-Red (ATR-FTIR, Nicolet 8500, USA) were used to in-
vestigate the structure of tribo-layer formed on the wear track. An
Electron Energy Loss Spectrometer (EELS, JEOL 2100F, Japan) and
Time-of-Flight Secondary Ion Mass Spectrometer (TOF-SIMS, PHI
TRIFT III, Japan) were used to characterize the structure of the tribo-
layer formed on the surface of wear spot.
indicated a change in the highly-ordered structure of BSA upon ad-
sorption onto the Co alloy.
3.3. TOF-SIMS of tribo-layer
Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) is a
versatile method to reveal, with high resolution, the chemical char-
acteristics of a surface. The TOF-SIMS spectra and mapping of the tribo-
3. Results
2 3
layers from inside the wear spot on the Al O after contact with the
different metals, as well as from the areas surrounding the wear spot
(i.e., outside the wear spot) are shown in Fig. 4.
3.1. Surface morphology and profile of wear track
As shown in Fig. 4a, the SIMS spectrum of the tribo-layer obtained
The microscope images of the wear tracks on the discs and the as-
2 3
from inside the wear spot of the Al O ball after wear contact with the
sociated wear spots on the Al
2
O
3
balls in contact with the respective
Co alloy in the BSA solution is similar to that of obtained from outside
the wear spot. The mapping of the wear spot of the alumina-Co alloy
pair (Fig. 4b) also shows that there is no obvious difference between the
inside wear spot and outside wear spot. This reveals that the chemical
surfaces, as well as the profiles of wear tracks are shown in Fig. 2. After
the wear test experiments with alumina balls in the BSA solution, ob-
vious furrows appeared on the surfaces of the metal discs (Fig. 2a and
b). Notably, a ‘black tribo-layer’ appeared in the wear track of the Cu
disc (Fig. 2a) that was absent in the wear track of the Co alloy (Fig. 2b).
The microscope images of the wear spot on the alumina worn with the
Cu and Co alloy discs are shown in Fig. 2c and d, respectively. The
2 3
nature of tribo-layer appearing on the wear spot of the Al O -Co alloy is
similar to that of the materials outside of the wear spot, indicating
further that the BSA molecules were not denatured or transformed into
a carbonaceous layer under friction between the alumina and the Co
612

Q.Y. Deng et al.
Surface & Coatings Technology 358 (2019) 611–616
Fig. 2. Microscope images of the wear tracks on the Cu (a) and Co alloy (b); the wear spot on the alumina from contact with the Cu (c) and Co alloy (d) discs; and the
profiles of both wear tracks (e).
Fig. 3. Raman spectra of dried BSA, inside and outside the wear track of the Cu (a) and the Co alloy (b) discs; and the ATR-FTIR spectra of dried BSA, the inside and
outside the wear track of the Cu (c) and the Co alloy (d) discs.
alloy. On the other hand, after the wear testing between the Al
2
O
3
ball
2 3
the Al O -Cu pair contained more hydrocarbon and carbon fractions
and the Cu disc in the BSA solution, the intensity of the SIMS spectrum
of the tribo-layer obtained from inside the wear spot is much higher
than that obtained outside of the wear spot (Fig. 4c). Further, the
than the surrounding areas of the wear spot. This further indicates that
the carbonaceous film was formed on the wear spot upon friction be-
tween the Al O and Cu surfaces in the presence of BSA.
2 3
mapping (such as C, C
spot is much lighter than that obtained from outside of the wear spot
Fig. 4d). This reveals that the tribo-layer from inside the wear spot of
2
, CH, etc.) of the tribo-layer from the inside wear
(
613

Q.Y. Deng et al.
Surface & Coatings Technology 358 (2019) 611–616
Fig. 4. The TOF-SIMS spectra of materials from inside and outside the wear spots of the Al
2
O
3
with the Co alloy (a) and the Cu (c) discs; and the TOF-SIMS mapping
2 3
of materials from inside and outside the wear spots of the Al O with the Co alloy (b), and the Cu (d) discs.
3.4. EELS spectra of tribo-layer
The electron energy loss spectroscope (EELS) is an excellent method
to confirm the formation of a carbonaceous film on the wear spot of
Al . After the wear test experiments in the BSA solution, a tungsten
2 3
O
probe was used to collect the sample (tribo-layer) from the wear spot
and then the EELS was used to investigate the structure of the tribo-
layer. The EELS results of a BSA control sample and the tribo-layers
obtained from the wear spots of the Al
pairs are shown in Fig. 5. The EELS spectrum of the tribo-layer from the
Al -Co alloy is similar to that of dried BSA, indicating that the
structure of the tribo-layer from the Al -Co alloy pair is similar to
2 3 2 3
O -Cu and Al O -Co friction
2 3
O
2 3
O
that of BSA. That is, the friction between alumina and the Co alloy did
not denature the BSA molecules to form a carbonaceous layer. Com-
pared with the spectrum of the dried BSA, however, the spectrum of the
Fig. 5. The EELS spectra of dried BSA and the tribo-layers on the wear spots of
the Al -Cu (denoted with white circle in Fig. 2c) and Al -Co alloy (denoted
with white circle in Fig. 2d) pairs.
tribo-layer obtained from the wear spot of the Al
vious π peak signal. This indicated that the tribo-layer formed on the
2
O
3
-Cu shows an ob-
⁎
2
O
3
2 3
O
2 3
wear spot of the Al O -Cu friction pair contained graphitic carbon; i.e.,
the friction between alumina and Cu can denature the BSA molecules at
the contact region to form a carbonaceous layer.
the Cu surface (Fig. 6b). It is expected that the friction between the
Al -Cu tribo-pair resulted in the release of Cu ions which promoted
2 3
O
the adsorption of the BSA molecules onto the wear tack of Cu surface.
In order to investigate the changes in the molecular weight of BSA
on the wear track of the Cu disc, the western-blot (WB) method was
used to characterize the molecular weight of the “tribo-layer” collected
from the wear track of the Cu disc. Dried BSA molecules were used as
the control sample. The result of the WB experiment is shown in Fig. 7.
The molecular weight of dried BSA is about 68 kDa (Fig. 7). There is an
3
.5. Adsorption of BSA on Cu
Fluorescein isothiocyanate (FITC) was used to investigate the ad-
sorption of BSA molecules onto the surface of Cu. The results are shown
in Fig. 6. Fig. 6a shows that the adsorption of BSA on the Cu surface
before wear testing is dispersive. After being subjected to wear testing
for 4 h, however, the adsorption of BSA intensified on the wear tack of
614

Q.Y. Deng et al.
Surface & Coatings Technology 358 (2019) 611–616
Fig. 6. Fluorescence images of BSA labeled with fluorescein isothiocyanate on a Cu surface before wear testing (a), and after wear testing in a BSA solution for 4 h (b).
obvious trailing behind this weight for the tribo-layer (denoted with a
red box). It is well-known that the smaller the molecule, the faster its
movement is in the separation gel (used in WB testing). This indicates
that some BSA molecules in the tribo-layer were denatured into smaller
molecules. That is, the friction between the alumina and the Cu surfaces
is sufficient to denature BSA, promoting its transformation into smaller
molecules.
4. Discussion
Carbonaceous films can lubricate the tribo-pair in an artificial joint
and suppress the ion releasing mechanism of metal ions [12]. Re-
searchers infer that this kind of carbonaceous film can be formed on the
surface of metals by the synergism of shear force and the catalytic
abilities of transition metals such as Cr and Co [12,13]. Cu is a transi-
tion metal and there are many researches that investigate its application
in the biomedical field [14–17]. The results of this work show that the
catalysis efficiency of the Cu ion is stronger than that of the Co ion with
regard to the formation of the carbonaceous layer on the surface of
wear contact regions. The result of adsorption experiments with fluor-
escein isothiocyanate (FITC, Fig. 6) shows that the BSA molecules are
obviously adsorbed onto the wear track of the Cu after wear testing
Fig. 7. The WB testing of dried BSA and tribo-layer on Cu. (For interpretation of
the references to color in this figure, the reader is referred to the web version of
this article.)
with an Al
which, in turn, is caused by the friction between the tribo-pair (Al
Cu). The released Cu ions would bond with the BSA molecules in
2 3
O ball in a BSA solution. This is due to the release of Cu ions
2 3
O -
Fig. 8. The schematic of formation of a carbonaceous film on the wear track of Cu in BSA solution.
615

Q.Y. Deng et al.
Surface & Coatings Technology 358 (2019) 611–616
solution to promote the adsorption of the BSA molecules onto the wear
track to form one “protein layer”. The schematic of this process is
shown in Fig. 8 (phases I, II, and III). This protein layer could subse-
quently transform into a carbonaceous film under the cyclic shear force
between the tribo-pair (shown in Fig. 8, phase IV). The wear resistance
of the tribo-pair would thus be improved and the further release of
metal ions would be suppressed. When the wear testing was performed
regions of the tribo-pair compared to the metal ions released from the
Co alloy.
What needs to be pointed out is that, pure Cu is not an ideal metal to
be applied in the production of artificial joint, due to the toxicity [18]
and the poor mechanical properties of pure Cu. The results of this work
show that the Cu ions are more efficient catalysts for the formation of
the carbonaceous film than Co ions. In the future research work Cu
doped films, such as Cu-TiN, Cu-DLC et al. can be fabricated for metal-
on-metal (MoM) artificial joint surface modification. When the Cu
doped film modified MoM joint servicing in human body, the Cu ions
can be released from the films under the friction between the artificial
joint tribo-pairs, and bond with the proteins in body fluid to promote
the formation of protein-layer on the surface of the friction interface.
And then this kind of protein-layer would transform to be carbonaceous
film by the synergism of the catalytic abilities of Cu and the shear force
between the tribo-pairs. This carbonaceous film can lubricate and heal
the wear of the Cu doped film. As a result, the wear resistance of the
tribo-pair would be increased and the lifetime of the modified artificial
joint in human body would be prolonged.
2 3
with the Al O -Cu tribo-pair in the BSA solution, a ‘black tribo-layer’
would appear in the wear track (shown in Fig. 2a) during the friction
process. The western-blot (WB) testing of this ‘black tribo-layer’ shows
that the molecular weight of the BSA collected from the wear track has
been denatured into smaller molecules (Fig. 7). This means the shear
2 3
force between the Al O -Cu tribo-pair was sufficient to denature the
BSA molecules in wear track. The structure tests of the tribo-layer
formed in the wear track of Cu show that there is an absorption peak at
−1
1
600 cm of the Attenuated Total Reflection Fourier Transform Infra-
Red (ATR-FTIR) spectra. This indicates that the structure of the BSA
molecules in the wear track have been denatured into molecules which
contain eC]Ce bonds (Fig. 3c). Both the Raman spectrum (Fig. 3a)
and the electron energy loss spectroscopy (EELS; Fig. 5) spectrum of the
tribo-layer formed on the Cu disc showed an obvious graphitic carbon
signal. The results of the Time of Flight Secondary Ion Mass Spectro-
metry (TOF-SIMS, Fig. 4) present similar results to the wear track ex-
periments; the carbon content inside the wear spot was much higher
than that outside the wear spot, indicating further that the tribo-layer in
the wear contact spot was a carbonaceous film. Thus, these results
corroborate that the release of Cu ions from the Cu surface could pro-
mote the protein adsorption onto the wear track to form a protein layer,
and the subsequent transformation of this protein layer into a carbo-
naceous film under the shear force between the tribo-pair (Fig. 8,
phases I to IV).
Acknowledgement
This study was supported by Natural Science Foundation of China
(31570958) and the Science and Technology Support Program of
Sichuan Province (2016SZ0007).
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[
[
2 3
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cannot transform the protein-layer into a carbonaceous film under the
conditions of this work. The resulting outcome is a poorer wear re-
sistance of the Al
pair (Fig. 2e).
2
O
3
-Co alloy compared to that of the Al
2
O
3
-Cu friction
[
5
. Conclusion
[
The ball-on-disc mode was used to investigate the formation of a
carbonaceous film in the contact regions of different tribo-pairs (Al
Co alloy and Al -Cu) in a BSA solution. The release of metal ions
[
2 3
O -
2 3
O
[
upon friction between tribo-pair can promote the adsorption of BSA
onto the wear track to form a “protein-layer”. This “protein-layer” can
transform into a carbonaceous film under friction conditions of the
Al
the Al
same conditions, however, this carbonaceous film cannot be obtained in
the Al -Co alloy tribo-pair. This reveals that Cu ions are more effi-
cient catalysts for the formation of the graphitic carbon on the contact
2
O
3
-Cu tribo-pair, and this carbonaceous film can in turn lubricate
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34–40.
2 3
O -Cu tribo-pair against further wear and ion release. Under the
2 3
O
616